Entomological Bulletin1)_whole.pdfNacerdes and Xanthochroa bear superficial resemblance to species of Idgia. In Hong Kong there is an unidentified species of Cantharidae (Figure 1)

Hong Kong Entomological Bulletin

Volume 3 (1) April 2011

Hong Kong Entomological BulletinThe Journal of the Hong Kong Entomological Society

Volume 3 (1) April 2011

EditorsChristophe Barthélémy ([email protected])Graham Reels ([email protected])

Contents

Aston, P.Prionoceridae Lacordaire 1857 of Hong Kong and Guangdong Province, China (Coleoptera;Cleroidea) . . . . . . . . . . . . . . . 2-6

Barthélémy, C.Notes on the biology of the conspicuous mud dauber wasp, Chalybion japonicum (Gribodo, 1883)(Sphecidae) a major predator of spiders in Hong Kong . . . . . . . 7-14

X.Q. Lee, J.A record of a group attack and occupation of a Vespine wasp nest by the hornet Vespa ducalis(Hymenoptera: Vespidae) . . . . . . . . . . . 15-19

Yiu, V.Observations on the luminescence configurations of eight firefly genera and their immature stages .. . . . . . . . . . . . . . . . 20-30

Cover photograph: Aggregation of males and females Chalybion japonicum; see p.12 (photo by ChristopheBarthélémy)

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Prionoceridae Lacordaire 1857 of Hong Kong and Guangdong Province 2

Prionoceridae Lacordaire 1857 of Hong Kong and Guangdong Province, China (Coleoptera; Cleroidea).

Paul Aston2nd Floor, 102 Wang Tong, Mui Wo, Lantau, Hong Kong.

Email: [email protected]

ABSTRACT

Notes on the identification of the six species ofPrionoceridae occurring in Guangdong Province and HongKong are given. Records, photographs and details of themale genatalia are provided for the Hong Kong species,together with remarks on the biology, flight period andmimicry.

INTRODUCTION

The Prionoceridae is a small family of three extant genera:Idgia, Prionocerus and Lobonyx containing around 150species (Geiser 2007), and is confined to the old world.Six species of Idgia have been recorded in Hong Kongand Guangdong, and Mayor (2007) lists another 14 speciesfrom China. Two species of Prionocerus have beenrecorded from China; both have extensive distributions andcould well occur locally (Geiser pers com.). Prionocerusdiffers from Idgia in having the third to tenth antennalsegments greatly broadened, flattened and serrate (seeGeiser 2010 for details on species identification). A singlespecies of the genus Lobonyx has been recorded in Chinaand differs from the other two genera in that the male hasonly two pectinate protarsal segments.

Historically theses genera have been placed in other familygroupings; most recently as a subfamily of the Melyridae;prior to that in the large family groupings ofMalacodermidae or Malacodermata. Champion (1919)revised the two genera Idgia and Prionocerus, but omittedmany species (Geiser 2007). Gressitt (1939) treated theChinese and Cochin-China species of the two genera, butdue to limited material only incorporated 10 species of Idgiain his key and descriptions, which was biased towards thesouth China species.

Species of Prionoceridae are elongate with thin, soft elytra,normally with rows of bristle-like setae. The head is drawnforward of the eyes forming a flat rostrum. The pronotumalways has a lateral costa and there are no costa on theelytra disk. Other features are emarginate eyes, tarsalformula 5-5-5, with simple tarsal claws and a single spuron the pro-tibia.

METHODS AND MATERIAL.

All specimens were collected, and site recordsdocumented, by the author in Hong Kong, with a biastowards Lantau Island. The genitalia were dissected and

were photographed in 100 % glycerine. All specimens arein the author’s collection.

MIMICRY.

Champion (1919) noted that the two Oedemeridae generaNacerdes and Xanthochroa bear superficial resemblanceto species of Idgia. In Hong Kong there is an unidentifiedspecies of Cantharidae (Figure 1) which is very similar toIdgia flavicollis Redtenbacher 1868. Also there are manyspecies with similar colouration to the Idgia species withblack tipped orange / yellow elytra, such as the oedmeridEobia chinensis (Hope) (see Figure 1); the Lampyridaespecies Luciola terminalis Olivier, 1883; and at least onespecies of Alleculidae. Whether this similarity is mimicry,some form of parallel evolution or other mechanism wouldbe speculative. These mimic-like species show few of thefeatures of Prionoceridae given in the introduction above.

Figure 1. Some mimic-like species of Idgia species.Top: Cantharidae sp. 16 May 2009 Tung Chung, Lantau.Bottom: Eobia chinensis (Hope) an Oedemeridae.


3 P. Aston

SEXUAL DIMORPHISM

The males of Idgia and Prionocerus species have apectinate black comb along the inner edge of the anteriortarsi (Figure 2), which is totally absent in the females. Thisis quite distinct in all species in Hong Kong, with theexception of Idgia oculata Redtenbecher 1868.

Figure 2. Protarsus of male I. flavirostris Pascoe1860.

KEY TO THE IDGIA SPECIES OF GUANGDONG (MODIFIED FROM

GRESSITT 1939).

1. Elytra largely pale (testaceous or orange) with darkapices …………………………. ..................................... 2- Elytra dark, usually dark blue or green, never orange or testaceous…………………....................................... 3

2. Prothorax rather evenly rounded at sides, edged withlong blackish bristles, surface smooth; head and apicalhalves of femora black; elytra with apical fifth blackishand external margins with blackbristles……………………....Idgia deusta Fairmaire 1878- Prothorax strongly narrowed behind middle, edged withmoderate brownish hairs, finely and sparsely granulose;head largely brownish or testaceous; only extremeapices of femora black; elytra with apical tenth or soblack, margins with small pale brown bristlesbristles…………………...Idgia ungulata Champion 1919

3. Head posterior of eyes blackish, and anterior ofantennal insertions light testaceous……………...……………………….........Idgia flavirostris Pascoe1860- Head anterior of antennal insertions mostlydark........................................................... .................... 4

4. Small species less than 12mm long ...........................................................Idgia flavicollis Redtenbacher 1868- Large species longer than 15mm............................... 5

5. Pronotum with a pair of blackish spots each side ofthe disc, Femora basally testaceous and dark (purplishbrown or bluish) apically .........................................Idgiaoculata Redtenbecher 1868- Pronotum immaculate, smooth and shaped similarly atapex and base; Abdomen metallic green on basal two-thirds; femora entirely metallic green...........…………..............Idgia hoffmanni Gressitt, 1939

SPECIES ACCOUNTS

Idgia flavicollis Redtenbacher 1868

Description: Length of Hong Kong specimens: 7-10mm.Shiny metallic green. Head green to shiny blue. Antennaeochraceous. Prothorax testaceous, more orange in olderspecimens. Pronotal disk smooth with a few bristles andmargin with sub-erect black bristles. Ventral surfacesbronzy green, with the apical two abdominal segments andtrochanter testaceous. Elytra micropunctate, thinly clothedwith recumbent golden-brown hairs and with rows of shorterect, black bristles.

Material examined: # 2 of 22.ii.09 Wang Tong on flowers;# 2 of 28.ii.09 Wang Tong on flowers; # 3 of 28.ii.09 WangTong on flowers; # 1 of 1.iii.09 Wang Tong on flowers.Female; # 2 of 1.iii.09 Wang Tong on flowers. Male; # 1 of5.iii.05 Mui Wo, Lantau; # 2 of 5.iii.05 Mui Wo, Lantau.

Site records: 20.ii.09 Wang Tong, Mui Wo, Lantau; 2.iii.08Wang Tong, Mui Wo, Lantau; 5.iii.05 Wang Tong, Mui Wo,Lantau; 7.iii.06 Wang Tong, Mui Wo, Lantau; 11.iii.06 WangTong, Mui Wo, Lantau; 13.iii.08 Wang Tong, Mui Wo,Lantau; 14.iii.08 Wang Tong, Mui Wo, Lantau; 17.iii.08Wang Tong, Mui Wo, Lantau; 18.iii.06 Mui Wo, Lantau;19.iii.06 Wang Tong, Mui Wo, Lantau; 21.iii.06 Wang Tong,Mui Wo, Lantau; 25.iii.06 Wang Tong, Mui Wo, Lantau;26.iii.06 Wang Tong, Mui Wo, Lantau; 27.iii.06 Wang Tong,Mui Wo, Lantau; 28.iii.06 Ngong Ping, Lantau; 2.iv.06Wang Tong, Mui Wo, Lantau; 5.iv.06 Wang Tong, Mui Wo,Lantau; 14.iv.05 Wang Tong, Mui Wo, Lantau; 17.iv.05Wang Tong, Mui Wo, Lantau; 18.iv.06 Wang Tong, MuiWo, Lantau; 26.iv.08 Wang Tong, Mui Wo, Lantau.

Biology: This is by far the commonest species ofPrionoceridae in Hong Kong. It is abundant in the last 2-3weeks of March with extreme dates of 22 February and 26April. Invariably seen in large numbers and found on almostevery indigenous blooming plant on the hillsides, mostcommonly on Maesa perlarius (Lour.) Merr.; Ligustrumsinense Lour.; Celtis sinensis Pers.; Zanthoxylumscandens Blume and Rhaphioepis indica (L.) Lindl.;Phyllanthus emblica L and Lonicera sp. I flavicollis seemsto favour indigenous species and has been observedfeeding on plants close to blooming, although this specieswas never observed visiting flowers of Agaretum sp,Lantana sp and Bauhinia sp. On 2 March 2006 during andafter very heavy rain many beetles of this species wereobserved sheltering under green painted metal railings.

Distribution: Hong Kong and Taiwan. Redtenbacher(1867) described this species from specimens collectedin Hong Kong by the Fregatte Novara expedition.



Figure 3. Idgia flavicollis : Top 5 March 2005 . Bottom: 17April 2005. Both Wang Tong, Mui Wo, Lantau

Figure 4. Idgia flavicollis Redtenbacher 1868. Left imago.Right from top. Male genitalia armature: A Lateral view BLateral view with medium lobe pulled away from the laterallobes. C Dorsal view D ventral view.

Idgia hoffmanni Gressitt, 1939

Description (from Gressitt 1939): Length 18.5mm. Metallicgreen and blue. Elytra, ventral surfaces and legs clothed

in sub-recumbent short pale tawny hairs. Head andpronotum covered in longer sub-erect or oblique blackbristles. Head steel blue with greenish tinge. Clypeusslightly purplish. Antennae pale ochraceous, base of scapepiceous. Clothed in very short pale golden hairs. Prothoraxorange yellow, sub-hyaline, slightly dark near apex andbase, clothed with black setae. Scutellum bronzy purple.Elytra metallic blue-green. Ventral surfaces shiny blueish-green. Last 2-3 abdominal segments and the sides of thepreceding sternites orange testaceous. Legs metallicgreen. Males: inner side of the first three segments of theanterior tarsi with distinct, close toothed black combsbeneath.

Distribution: Known only from a few specimens (Geiserpers.comm.) from Lien district in north Guangdong.

Idgia oculata Redtenbecher 1868

Description: Length of Hong Kong specimens: 15.5-18.5mm. Head steel blue to purplish. Antennae testaceous.Prothorax testaceous with a round purplish-edged, blackspot each side of the centre of the disk, sparsely coveredwith long semi-decumbent golden pubescence and sparsesemi-erect and shorter black setae. Scutellum darktestaceous to bluish (brighter testaceous in one livespecimen). Elytra metallic blue to greenish blue.Metasternum blue green. Abdomen testaceous. Legspurple to black with coxae and basal halves of femoratestaceous.

Material examined: # 23 of 25.v.10 Ng Tung Chai; # 24 of25.v.10 Ng Tung Chai; # 1 of 17.vi.08 Lam Tseun Valley ; #6 of 22.vi.09 Ng Tung Chai # 2 of 26.vi.07 Upper LamTsuen valley. Site records: 1.vii.08 Shing Mun; 6.vii.08Kap Lung.

Figure 4. Idgia oculata. 17 June 2008 Lam Tseun Valley

Biology: Flight period centred around June with extremedates of 25 May and 6 July. Normally encountered in largegroups, feeding on various flowering shrubs and trees.Observed on 17 May 2008 on leaves of Mallotuspaniculatus (Lam) Muell. Arg.

Distribution: Hong Kong and Hainan. Redtenbacher(1867) described this species from specimens collectedin China by the Fregatte Novara expedition (which at thattime could have included modern day Kowloon or the NewTerritories). The first reference to this species in Hong Kongwas made by Hill (1982) and Hill et.al (1982). Mayor (2007)lists only Hainan and not Hong Kong for this species. Geiser(pers.comm.) has noted that Pic (1923) had recorded thisspecies from Tonkin.

5 P. Aston


Idgia ungulata Champion 1919

Description: Length 8-10mm. Pale orange testaceous.Antennae, basal portion of head, extreme apices of elytra,tibiae and tarsi and apical one-tenth of elytra pitchy brown.Eyes almost contiguous on top of the head in males.

Material examined: # 3 of 22.iv.06 Wo tin, Mui Wo,Lantau; # 10 of 27.iv.08 Wang Tong , Mui Wo, Lantau; # 1of 7.v.07 Wang Tong , Mui Wo, Lantau; # 3 of 9.v.06 Silvermine waterfall, Mui Wo, Lantau; # 12 of 16.v.10 Ng TungChai.

Site records: 12.v.09 Wang Tong

Biology: Always found singly. Attracted to lights. Onespecimen was netted at dusk in flight. Normally found inthe daytime under leaves with no sign of feeding.

Distribution: Widely distributed in eastern China.Champion (1919) described this species from specimenscollected in Hong Kong Kong by J.J. Walker and F.W. Terry,as well as specimens collected from Amoy.

Figure 5. Idgia oculata. Left imago. Right from top. Malegenitalia armature: A Lateral view B Lateral view withmedium lobe pulled away from the lateral lobes. C Dorsalview D ventral view.

Figure 6. Idgia ungulata 22 April 2006 Mui Wo, Lantau.

Idgia deusta Fairmaire 1878

Description (from Gressitt 1939): Length 9.5-12mm.Orange testaceous. Antennae, head, tibiae and apical one-fifth of elytra, black. Elytra with longitudinal rows of blackbristles.

Distribution: Widely distributed in south and east Chinaand Vietnam. Gressitt (1939) recorded this species fromGuangdong, but it has not yet been recorded in Hong Kong.

Idgia flavirostris Pascoe 1860

Description: Length of Hong Kong specimens: 9.5-11mm.The bicoloured head makes this species quite distinctive.Base of head to the posterior of the antennal insertions,dorsally, and to the anterior of the eyes ventrally, blackwith a green or purple tinge. Anterior of the head includingpalps and antennae, testaceous. Pronotum subquadratewith the posterior two-thirds slightly sinuate, all marginsedged with erect black setae. Elytra green to bluish green,sometimes with a red or purple tinge, granulate, thoughshining. Each elytron with 6-7 rows of erect black setae,the rows becoming less distinct and confused in theposterior third. The antennae from segment four to apex,tarsi, meta and mesa tibiae are darker and have a reddishtinge, though in one specimen this is almost black.Metasternum dark greenish blue. The abdomen in theHong Kong specimens is testaceous, the disc of the 3 basalsegments being slightly dingier. This differs from Pascoe’s(1860) description of the abdomen of the type, being blackwith yellow margins.

Material examined: # 1 of 21.ii.09 Tung Chung Uk, Lantau;# 5 of 26.ii.10 Po Lin, Lantau; # 6 of 26.ii.10 Po Lin, Lantau;# 7 of 26.ii.10 Po Lin, Lantau; # 1 of 8.iii.08 Tung Chungvalley, Lantau; # 2 of 8.iii.08 Tung Chung valley, Lantau.

Figure 7. Idgia ungulata. Left imago. Right from top. Malegenitalia armature: A Lateral view B Lateral view withmedium lobe pulled away from the lateral lobes. C Dorsalview D ventral view.



Figure 8. Idgia flavirostris. 8 March 2008 Tung Chung valley

Biology: Flight period from 21 February to 8 March. Allrecords are in well wooded areas above 350m altitude.Mostly seen singly or in very small groups. Observed onblooming Maesa perlarius (Lour.) Merr. and Ligustrumsinense Lour.

Distribution: Southeastern China including Hong Kong.Mayor (2007) lists only southeast China for this species,even though Pascoe (1860) described the type fromnorth China.

ACKNOWLEDGEMENTS

I am grateful to Michael Gieser, Natural History Museum, Basel,Switzerland for his valuable advice, comments and corrections on thedraft of this paper and to Graham Reels, HK for proof reading the

manuscript.

REFERENCES

Champion, G. C. 1919. The Malacoderm GeneraPrionocerus and Idgia and their Sexual Characters(Coleoptera). Annals and Magazine of Natural History, Ser.9, 3, 325–372; plates 11 & 12.

Geiser, M. 2007. Studies on Prionoceridae (Coleoptera,Cleroidea). I. A new species of Prionocerus Perty, 1831from Sumatra. Entomologica Basiliensia et CollectionisFrey 29: 167–170.

Geiser, M. 2010. Studies on Prionoceridae (Coleoptera:Cleroidea). II. A revision of the genus Prionocerus Perty,1831. Zootaxa 2328: 1–48.

Gressitt J.L. 1939. Some Prionoceridae from China,Hainan, Formosa and Cochin-China (Coleoptera). LingnanScience Journal (Canton) 18: 187-196.

Hill, D.S. 1982. Hong Kong Insects. Volume II. UrbanCouncil, Hong Kong.

Hill, D.S., Hore, P.M. & Thornton, I.W.B.1982. Insects ofHong Kong. Hong Kong University Press.

Mayor A. 2007. Prionoceridae. Catalogue of PalaearcticColeoptera. Vol 4. Elateroidea - Derodontoidea -Bostrichoidea - Lymexyloidea - Cleroidea - Cucujoidea.Löbl, I. & Smetana, A. eds. pp384-386.

Pascoe F.P. 1860. Notices of new or little-known generaand species of Coleoptera. Journal of Entomology 1: 36-64.

Pic, M. 1923. Etudes des Malacodermes de l’Indochinerecueillis par M.R. Vitalis de Salvaza.I In : FauneEntomologique de l’Indochine Francaise (Vitalis de Salvazaed,)., Opuscules de l’Institut Scientifique de l’Indochine,Saigon, 1 : 1.137.

Redtenbacher, L. 1867. Zoologischer Theil. Zweiter BandI. Abtheilung A. 1. Coleoptera. In: Reise derOsterreichischen Fregatte Novara um die Erde in derJahren 1857, 1858, 1859 unter der befehlen desCommodore B. von Wüllerstorf-Urbair. Wien: Karl Gerold’sSohn, iv +249 pp. + 5 pl.

Figure 9. Idgia flavirostris. Left imago. Right from top. Malegenitalia armature: A Lateral view B Lateral view withmedium lobe pulled away from the lateral lobes. C Dorsalview D ventral view.

7 Notes on the biology ofChalybion japonicum


Notes on the biology of the conspicuous mud dauber wasp, Chalybion japonicum (Gribodo, 1883) (Sphecidae)a major predator of spiders in Hong Kong.

Christophe Barthélémy Sai Kung Country Park, Hong Kong,

E-mail: [email protected]

ABSTRACT

The nesting biology of Chalybion japonicum was studiedusing nest traps in Hong Kong. It was revealed that (i) thiswasp was very versatile in nesting site selection, (ii) itconstructed few cells per nests (83% of the nests studiedhad one or two cells only), (iii) there was a variability inprey selection related to the seasonal abundance of prey,(iv) that nearly 40% of all brood died during developmenteither from fungal infection or parasitism and (v) that thismud dauber was bivoltine in Hong Kong.

Key words: Chalybion japonicum; Sphecidae;Araneidae; nest-traps; parasitism.

INTRODUCTION

This paper describes the nesting biology of the commonmud dauber wasp Chalybion japonicum in Hong Kong.Observations were carried out in 2010 using nest trapsthat were dissected and nesting behaviour was recordedin-situ.The genus (sub-genus) was revised by Hensen (1988) whoprovided a grouping of the various species; C. japonicumwas placed in the C. bengalense Group. Members of thisgenus have generally distinctive metallic hues of blue orgreen, only one member being black.Chalybion japonicum is widely distributed from the KoreanPeninsula, Japan, Taiwan and South East Asia (Yamaneet al 1999).

MATERIALS & METHODS

The nesting behaviour of Chalybion japonicum was studiedusing nest traps that consisted of hollow bamboo canes ofvarious length and diameters that were cut so that oneend was closed by a nodal septum. Clusters of seven cutcanes were bundled together and hung from roof beamsin the author’s office in Sai Kung Country Park, Hong Kong.

A total of 64 traps were set in April, May and June 2010 inthe same location. The April and May traps were 155-185mm long (mean = 164.8; n = 50) with diameters of 6-10mm (mean = 7.6; n = 50), while the June traps were165-230mm long (mean = 203.9; n = 14) with diametersof 6-10.5mm (mean = 7.5; n = 14). Upon collection, aftercompletion of the nest by the wasp the traps were opened,prey, brood content and nest associates recorded and thetraps then placed individually in Ziploc® bags for broodemergence.

Ten freshly completed nests totalling 12 cells were openeddaily, the brood was measured, prey numbers and speciesdetermined and daily prey consumption measured until thelarvae pupated, after which the nests were left undisturbeduntil emergence of adults. The daily growth wasdocumented photographically.

Measurements were taken on scaled photographicenlargements for brood and with a precision stainless steelcalliper for nest dimensions, cell partition and cocoon wallthickness.Spider prey where identified by Dickson Wong Chi Chun,Hong Kong, based on my photographic records.

Additionally, I carried out in-situ observation of nestconstruction and prey provisioning on four traps, totalling6hrs 08mns of observation.

OBSERVATIONS & DISCUSSION

Nest & brood description

Nest architectureChalybion japonicum was extremely versatile with regardsto nesting site selection, beyond the frequent usage of myobvious traps, the wasp selected any site that wouldpresent itself with a more or less tubular shape, whether itbe the screw recesses in electrical appliances, cells of anest of Polistes gigas, left on a table top, the cellsconstructed by Sceliphron deforme the previous year (Fig.1) or even interstices between rafters and joists of the roof.It was also observed opening fresh Sceliphron deformecells, empty the content, prey and brood alike and thenfurnish it with its own prey and brood.

The nests contained few cells generally, 39% of the nestswere composed of one cell, 44% had two cells,14% hadthree cells and 3% had 4 cells, regardless of the tube lengthor diameter. As was noted by Iwata (1976) the wasp doesnot utilize fully the cavity at hand, leaving considerableempty space either in the cell or beyond it, as opposed tomany other tube-renting wasps in the family which optimisespace utilisation.

The nests could be characterised by the following: (i) theinnermost cells did not necessarily start from the bottomof the trap, but could be initiated anywhere along its length,(ii) there were no intercalary cells, (iii) the outermost cellanterior partition formed the nest closure and (iv) whenthe first cell was initiated against the nodal septum the


C. Barthélémy 8

wasp generally did not add a plug of cell material at theposterior end of the cell. Figure 2 gives an illustration of atypical nest at opening.

The cell partitions were composed of a clayish materialwith inclusions of sand grains, in all cases the posteriorside of the cell partitions had a rough finish while theanterior surface was smooth. A great variety of forms ofclosures where observed, from a simple clay partitionmaximum 3mm thick, with or without adjunction of afinishing layer, to complex multipartitions constructions,separated with narrow empty space and thick nest plugs,with or without a finishing layer. In 14% of the cases C.japonicum applied an additional layer of white material -likely uric acid from reptile faeces (Gekko spp) - on thelast cell partition on both uni- and multi-cellular nests; inanother 14% it would apply patches or even layers of agrey/black material likely to be faecal matter and in 14% itapplied a layer of transparent resinous material (from anunknown plant source) to the same. Iwata (1964) notedthat the usage of white material was an obligate behaviouron all nests of the specimens he observed in Thailand andthat such was the case for uni-cellular nests in Japan(Iwata, 1976); however, as shown here this behaviour wasmore facultative in Hong Kong with a large degree ofvariability. The use of white material has been recordedfor several other species in the genus (C. bengalense andC. zimmermanni) (Jayakar and Spurway 1963; Ward 1971).Iwata (1976) observed the wasp collecting gum from peachtrees and applying it to the nest closure.

The nests had no vestibular cell, although one trappresented a succession of three partitions after the singlecell. It may be possible that this was the consequence ofan attempt by the original wasp or even another one toadd additional cells to the cavity. All but two traps had noposterior partition to the first cell and two other traps hadsome cell partition material applied on or very close to thenodal septum of the hollow cane.

When multi-cellular nest were built the first cells werelonger than the second which were longer than the third.The first cells were 22-190mm in length (mean = 104mm;n = 64), the second cells were 23-84mm (mean = 44mm;n = 38), the third cells were 26-116mm (mean = 33mm; n= 11) and the fourth cells were 19-32mm (mean = 25.5; n= 2).

Prey and ovipositionThe vast majority (90%) of prey were in the Araneidaefamily,7.8% in Tetragnathidae (all represented by fourspecies of Leucauge), 2% in Theridiidae and 0.2% inUloboridae. In fact the majority of all prey were representedby two genera in Araneidae, 49% in Neoscona spp and33% in Cyclosa spp. Males and females were providedalthough females represented 79% and males 21% of allprey taken. There were between 5 and 18 prey items per

cell (mean = 10.5; n = 47). C. japonicum is a major predatorof small spiders. Between the 12 April 2011 and 10 May2011 the first adults (from overwintering pupa) took 251prey items distributed over 21 recorded nests (12 preyitems per nest) and between the 29 May 2010 and 17 July2010 the daughters took 234 prey items on seven nests(33.5 prey items per nest).

A generational variation was noted in the major species ofprey taken. The first active females of the yeartook a majority of Neoscona spp., while their daughterstook a majority of Cyclosa spp. with Neoscona spp.completely absent from the prey records. This absencemay be explained by two independent factors: theexhaustion of the prey stock after intensive hunting by thefirst generation, and/or the end of the seasonal presenceof the spider species from mid to end of June onwards .David A. Landes (Landes et al 1987) noted that C.californicum in the Southern USA clearly selected preyaccording to their seasonal abundance and this may wellbe the case with C. japonicum in Hong Kong.The difference in prey number presented above may beexplained by the distinctive seasonal prey preferencebetween the first active females and their daughters:Neoscona spp. are generally larger than Cyclosa spp.; atleast in the prey record and the nesting female wouldrequire more prey matter to sustain its brood.

The egg was attached dorso-laterally close to the abdomenand cephalothoracic junction of the prey, the anal endapproximately median to the host body (Figure 4). On the32 cells for which the position of the egg was ascertainedfour were found to be laid on the first prey, seven on thesecond, five on the third, four on the fourth, one on thefifth, three on the sixth, three on the seventh, three on theeighth and one each on the ninth and thirteenth prey. Thisclearly shows that C. japonicum lays its eggs afterprovisioning the cells as is the case with many apoid wasps,but there was no particular determinism in the egg position.

On five nests for which prey and sex of brood wasdetermined it was noted that the mother provided fewerprey for males than for females (Table 1).

Table 1: Prey item count relative to the sexof the brood


9 Notes on the biology ofChalybion japonicum

Brood and brood developmentBrood development was monitored at 24 hour intervals on10 traps totalling 12 cells, until the brood reached pupationperiod (Figure 3).

The egg was creamy in colour slightly arched, withhemispherical ends and a more or less constant diameterof 0.8-0.94mm (mean = 0.86mm; n = 29), it was 2.9-3.6mmlong (mean = 3.20mm; n = 27). It hatched in approximatelyfour days after oviposition (mean = 3.80 days; n = 12).The first instar larvae remained attached to the prey andfed ventrally on the prey abdomen until it was emptied; itthen reached for other food items moving about in the cell.At first the larvae only consumed the abdomens of theprey leaving cephalothoraxes and appendages, however,when all prey had been fed upon the larva consumed whatwas left, leaving nothing save for a few hard chitinouselements such as the chelicerae. The larvae fedcontinuously for about 7 days (mean = 6.80 days; n = 10).In the first four days, the number of prey consumed dailyincreased and on the fourth or fifth day it suddenlydecreased. The daily mean larval growth and preyconsumption is expressed graphically in Figure 4. Whenfeeding was completed the larvae groomed themselves,removing foreign objects such as prey setae and hardchitinous parts from their bodies. On the first day aftercompletion of feeding the larvae would spin lose strandsof silk in an apparent random fashion binding them to thecell walls; they then proceeded at the construction of thecocoon proper within the tangle of the loose strands, thistime spinning a dense film of fine silk forming a continuouslayer for about two days. It took 3-4 days (mean = 3 days;n = 10) to complete a cocoon and start pupation. The silkof the cocoon was at first creamy-white and graduallydarkened in three days to become dark brownish-red,barely translucent. It was fragile and easily torn. Thecocoons were oblong, with a basal hard and dark capsuleand were 17.50 - 25.20mm long (mean = 21.20mm; n =24) with a maximum diameter of 4.50 – 6.70mm (mean =5.60mm; n = 24) the wall thickness was 0.08mm thick.

Pupation time was measured untill emergence from thenest and lasted 39-42 days (mean = 40.80 days; n = 9).However, from casual observations it seems that afterbreaching the cocoon the wasp remained inside the trap/nest for a day at maximum and then emerged.

As a rule males emerged before the females, and femalescells were always constructed before (posteriorly) to thatof male, although in one instance the mother constructeda male cell before the female one.

VoltinismObservations on nesting patterns revealed that C.japonicum had two generations per year. The firstgeneration emerged from overwintering brood in May andthe second emerged in June. Two distinct ovipositioningactivity periods were noted, the first in May and the second

from end of June to Mid-July. The larvae entered a longdiapause in July, overwintering as pre-pupal larvae untilend of April of the following year when pupation started.

Sex ratioSex ratio was obtained on 37 active cells and wasdetermined to be 25 females for 12 males or anapproximate ratio of 2:1.

Natural enemies, nest associates and brood deathA number of enemies and associates were reared fromcells of C. japonicum. Twenty-eight cells out of 105 (27%)were parasitised. The most common enemy was acleptoparasitic phorid fly which was present in 19 cells,seven cells were infested by Melittobia sp (Chalcidoidea,Eulophidae), one cell was parasitised by a cleptoparasiticmiltogramine fly and the brood in one cell seemed to havebeen destroyed by an infestation of small Psocoptera.

and fresh prey was noted on several nests (Figure 5), thisindicates that the fly gains access to the cell while it isbeing built, it remains trapped inside at cell closure, and isthen at leisure to lay eggs both on the prey and the cellwalls. The wasp egg is likely consumed by the adult fly asno eggs were ever found when the parasite was still ategg stage. The maggots never consumed the entire foodstore and left a great volume of prey matter.

On the other hand Melittobia sp. attacked only maturelarvae, pre-pupae and pupae, therefore the Chalcidid musthave gained access much after the nest and its closurehad been completed.

Small Psocoptera were found in 10 nests. They werepresent from the beginning untill much after broodemergence. They seemed to feed on debris in the nestrather than on the wasp brood save for the single casementioned above.

Mites were recorded in two instances on the brood andlater on the adult wasp when it was collected at emergence.

The brood died for reasons not related to parasitism in 12out of 112 active cells (11.7%). Fungal infection was presentin nine of these cells and is the presumed cause of mortality,although in some instances despite the presence of mouldon the prey, the brood developed, pupated and emerged.When combined with parasitism the total brood failurereached approximately 39%. O’Neil (2001) provides asummary of brood mortality for a few species of Sphecidaeand in particular for four species of Sceliphron, a closerelative to Chalybion. This ranges from 36% to 43% whichcoincides with the brood mortality observed in this study.

In-situ observationsIn-situ observation totalling over six hours of activity onfour traps was carried out in May-June 2010. Behaviours

C. Barthélémy 10


were time recorded. Five major activities were identified:(i) cell material foraging: (ii) prey foraging; (iii) applyingcell material; (iv) placing prey and (v) other activities,referred to as unknown. Table 2 details the time spent oneach of the above activities, Table 3 provides the durationof each activities for the construction of one cell and Figure6 graphically illustrates the nesting activities sequences.

Work started soon after sunrise around 0700h locally (inMay) and stopped before sunset around 1800h, the waspsheltering for the night away from the nesting site.On a cell the wasp spent 60% of her time foraging forprey, 28% foraging for cell material, 9% applying thismaterial to the cell partition, 0.5% placing prey in the celland 2.5% as unknown time spent. To construct andprovision one cell the wasp took on average 3hrs50minand could therefore construct a 2-3 cell nest in one day.The cells were never closed by a temporary plug when thewasp left for foraging.

Nest constructionThe cell partition material was formed into a small pelletand was carried solely with the mouth parts, mandiblesand possibly palpi/bristles (?). One wasp, using bundlePSO-104, procured the mud from an old Sceliphrondeforme nest, approximately 1m away, a fact that had beenobserved with C. californicum and C. zimmermanni onnests of Sceliphron (Bohart & Menke 1976). The use of adry source of material requires water to render it plastic,therefore it can be confirmed for C. japonicum (Bohart andMenke 1976) that water is procured first and then appliedto a source of dry mud. When the material was appliedinside the nest, the wasp produced a stridulating noise

similar to that of other Sphecoidea, caused by thecontraction of the longitudinal wing muscles of the thorax.

Upon completion of a cell partition the wasp always lingeredat the nest entrance (2-10s), grooming and often re-entering the trap (up to five times) as if inspecting theworkmanship.

In some cases when provisioning was incomplete at theend of the day the wasp would leave the cell open for thenight resuming work the following day.

In several instances although the terminal partition hadbeen constructed, it was re-worked upon several days afterthe nest had been completed, with the addition of a layerof white material, assuming it were the same wasps. Also,in two instances it was observed that wasps could breachthe terminal partition of a completed nest, extract some ofcontent of the last cell – never more than 1-2 prey items,and later reseal the nest. Usurpation of nests of S. deformewas a common occurrence, the two species co-existing inthe same locale. C. japonicum re-used either breachedcells or simply breached an occupied cell, extracted thecontent, either pupa, larva or prey and furnished it with itsown prey and egg, sealing the cell upon completion ofprovisioning. Not having marked live specimens anddespite the incident related above, it was unclear if C.japonicum showed defined intraspecific nesting siteusurpation. Species in the genus have a tendency towardsinterspecific nest usurpation such a C. californicum uponnests of Sceliphron spp. (Bohart and Menke, 1976) andthis was confirmed with the present study by C. japonicumupon nests of S. deforme although from casualobservations it seems that C. japonicum may prefer pre-existing cavities over old nests.

Prey transportation and provisioningThe mode of transportation varied according to the preysize. While in general all prey were of similar size,occasionally the wasp would carry exceptionally small items(Cyclosa sp1). Large prey were carried venter up, the frontlegs seized by the mandibles and the body held with thewasp fore-legs. Small prey were carried similarly but heldonly by the mandibles, un-assisted by the forelegs.

The wasp entered the nest head first, dragging the preyunder her body and always exited metasoma first beingunable to rotate herself within the cavity.

On several occasions the wasp delivered additional stingsto the prey before entering the trap, as if it had assessedthat the item was insufficiently paralysed, behaviour thatmight have been confused with oviposition by Yamamoto(1942).As with cell partition construction, the wasp alwayslingered at the nest entrance upon completion of preyprovisioning, often re-entering the tube for some kind ofinspection.

Table 2: Recorded activities, time budget.

Table 3: Activities durations for theconstruction of one cell.

11 Notes on the biology of Chalybion japonicum


Interactions with conspecificsChalybion spp are known to form “sleeping” aggregations(Bohart and Menke 1976) and this was observed for C.japonicum in one instance where males and femalesaggregated on a loose hanging piece of rope (Figure 7).

The wasp was fiercely defensive of her nesting site andindividuals would actively grapple and chase away intrudingcon-specifics that came to close to their nest.

MatingMating was witnessed in May 2010. A Ficus tree coveredin Honey suckle overlooked by my office was a favouriteresting/foraging(?) ground for many of the specimens thatnested in the office. Here I saw several females beingswarmed by males; the encounter lasted for about 10seconds.

CONCLUSION

The observations that were made seem to conform to whatis known about the biology of this wasp. However, it wasnoted that not all nest plugs were finished by a layer ofwhite material contrary to the assertion by Bohart andMenke (1976) that “all” species save for C. californicumdo so.The variability of prey choice from one generation to theother warrants further analysis in order to ascertain thelife cycles and abundance of the chosen prey.

ACKNOWLEDGMENTS

I am grateful to Alexander V. Antropov, Senior Scientist and Curator ofHymenoptera collections Zoological Museum of Moscow StateUniversity, Moscow, Russia for the comments and suggestions madeto the original manuscript.Graham Reels provided a thorough proof-reading of the original manuscript and helped with its clarity.

REFERENCES

Bohart, R.M. & Menke, A.S., 1976. Sphecid wasps of theworld. A Generic Revision. University of California Press,695pp.

Hensen, R.V. 1988. Revision of the nominate subgenusChalybion Dahlbom (Hymenoptera, Sphecidae). TijdschriftVoor Entomologie 131:13-63.

Iwata, K., 1964. Bionomics of non-social wasps in Japan.Nature and Life in Southeast Asia 3:323-383.

Iwata, K., 1976. Evolution of Instinct. The ComparativeEthology of Hymenoptera. Smithsonian Institution &National Science Foundation, Washington, D.C., translatedfrom Japanese. 535pp. Figure 1: Nesting site versatility in C. japonicum. Top left:

re-usage of cell of Sceliphron deforme. Top right: screwrecess as a nesting site. Bottom: Cells constructed in anold comb of Polistes gigas.

Landes. A.D., Obin, M.S., Cady, A.B and Hunt, J.H. 1987.Seasonal and Latitudinal Variation in Spider Prey of theMud Dauber Chalybion californicum (Hymenoptera,Sphecidae). Journal of Arachnology 15:249-256.

Jayakar, S.D. & Spurway, H.1963. Use of VertebrateFaeces by the Sphecoid Wasp Chalybion bengalenseDahlb. Journal of the Bombay Natural History Society60(3): 748-749.

O’Neil, K.M. 2001. Solitary Wasps. Behavior and NaturalHistory. Comstock Publishing Associates. 406pp.

Yamamoto, D.1942. Habits of Sceliphron (Chalybion)inflexum Sickmann. Kontyu 16:69-75.

Yamane, S., Ikudome, S., Terayama, M. 1999. IdentificationGuide to the Aculeata of the Nansei Islands, Japan.Hokkaido University Press, Sapporo. 831pp.

FIGURES

C. Barthélémy 12


Figure 3: Brood development

Figure 7: Aggregation of males and females C.japonicum.

Figure 2: Typical nest content a opening. Top: trap PSO-102.A3 composed of two cells. Bottom: the prey and

brood content of the same trap (photo author).

Figure 4: Prey consumption and brood growth.

Figure 5: Phoridae cleptoparasitism captured at trap opening (photo author).

13 Notes on the biology of Chalybion japonicum


C. Barthélémy 14


Figure 6: Nesting activities sequences


15 Group attack of a Vespine wasp nest by Vespa ducalis

A record of a group attack and occupation of a Vespine wasp nest by the hornet Vespa ducalis (Hymenoptera:Vespidae)

John X.Q. LeeNo. 2, 2/F, Sai Wang Lane, Sai Kung, N.T.

Email: [email protected]

ABSTRACT

A record of an incident in which multiple workers of thehornet Vespa ducalis Smith, 1852 were found occupyinga nest of another hornet species is reported. This behaviouris unusual in that this species has not previously beenknown to attack other vespine wasps, nor has it beenrecorded for more than a single forager to occupy a preynest.

INTRODUCTION

This paper describes observations on multiple individualsof the hornet species Vespa ducalis Smith, 1852 occupyinga nest of Vespa bicolor Fabricius, 1787, a smaller speciesin the same genus. Vespa ducalis is usually a specialisedpredator which preys almost exclusively on nests ofpolistine wasps and attacks them individually. This is tothe author’s knowledge the first published record of V.ducalis occupying the nest of a vespine wasp, and alsothe first record of it occupying a prey nest in a group.

NOTES ON VESPA DUCALIS

Vespa ducalis is a widely distributed hornet species with arange including India, Nepal, Burma, Thailand, Vietnam,South China, Taiwan, East Russia and Japan. It forms thesmallest colonies among all known Vespa species(Matsuura and Yamane 1984) and has the shortest colonycycle among all species in Japan (Matsuura 1991) andHong Kong (Lee 2009), an attribute which is possibly linkedto its very specialised feeding habits (Archer 1991;Matsuura 1984; Matsuura and Yamane 1984); new queensemerge and initiate nests only after various species ofpolistine wasps have already established their nests, andcolonies die off earlier than other Vespa species as polistinecolonies become void of immatures and food thusbecomes unavailable.

V. ducalis is known to prey almost exclusively on polistinewasps such as Polistes and Parapolybia, and to attacksingly, preying only on the brood and never harming theadult occupants. Its usual hunting method involves a singleindividual searching around locations where polistinewasps often build nests, such as in and around small trees,shrubs and under eaves and ledges of buildings (pers.obs.). When a target nest is found, the hornet lands on itand proceeds to pull out the brood, biting off cocoon capsin the process. Prepupae appear to be the preferred choiceand are often taken first, followed by pupae, and lastly large

larvae. Small larvae are usually either taken last or totallyignored. The adult occupants generally flee the nest,offering little or no resistance. They gather near the nestand return to it after the attacker leaves. V. ducalis is usuallycontent to drive the original occupants away long enoughfor it to remove as much prey as it can; as a rule it doesnot harm the adult polistine wasps. This is in common withits close relative Vespa tropica (Linnaeus, 1758), whichshows the same dependency on polistine wasp nests inHong Kong. It must be noted that many older Japanesetexts discussing “V. tropica” in fact refer to V. ducalis, astrue V. tropica are not known from Japan.

OBSERVATIONS

A nest of V. bicolor was discovered at Kau Tam Tso (nearWu Kau Tang in the Northern New Territories) by the authorin May 2009, as an embryo nest with several pupae. Itwas built within an old nest of the same species in anabandoned village house, a common habit with V. bicolor(pers. obs.). By August 2009, the nest was spherical andthe envelope measured about 12cm in diameter andvertical length; when dissected and collected after theattack it was found to contain roughly 165 cells in twocombs. The exact number of wasps in the nest was notknown, though nests of similar size within the same timeof the year often contained 50 to 60 workers (pers. obs.).The author regularly visited and observed the nest fromMay to August at intervals of one to two weeks.

On 23 August, accompanied by Chan Kam Wah, the authorvisited the locality and found the nest void of the originaloccupants. Instead, a few workers of V. ducalis hadoccupied the nest. There appeared to be a total of five orsix individuals involved in the occupation. Shortly after wearrived at the locality, two individuals left the nest with theircrops full of body fluids from the prey (see discussionbelow). Two wasps remained outside on the envelope,while another two were inside the nest, consuming thebrood. Three of the wasps left shortly after, leaving one inthe nest, but another two came to the nest; it is not clear ifthese were the two which we first saw leaving. Theenvelope was intact and in a good state of repair, apartfrom the entrance hole which appeared to have been bittenand enlarged, probably by the attackers. After observingand taking photographs for a period of approximately tenminutes, we broke the envelope to facilitate observation.While V. ducalis is an exceptionally placid species whichoften does not attack even when its own nest is disturbed(Matsuura 1984; Lee, 2009; pers. obs.), the wasps were


J. X.Q Lee 16

visibly agitated when the envelope was broken, buzzingaround it but refusing to leave. This clearly showed thatthey were in the occupation phase.

There were only a few smaller larvae left in the nest by thetime the occupation was discovered. As it is normal for V.ducalis to attack pupae and larger larvae first, this isn’tconsidered unusual. The following day, I returned and foundthe nest totally void of brood, with only eggs remaininguntouched. The occupiers had completely abandoned thenest. This suggests that they had progressed to the finalstage of the occupation phase by the time we came uponit. Two weeks had elapsed since the last time the nest wasobserved, and it was not possible to estimate the totallength of the occupation phase. It is not clear how the V.ducalis came to occupy the nest, nor could we confirmthat the slaughter phase took place or that the originaloccupants were in fact killed by the V. ducalis and not bysomething else. However, we did find numerous dead V.bicolor with mutilated bodies scattered on the ground belowthe nest, most with missing legs, wings and antennae andsome even with severed heads and abdomens. Thus it ishighly probable that the group of V. ducalis did actuallyattack and overpower all the occupants of the nest (seediscussion).

DISCUSSION

Many species of hornets have been known to attackhoneybees at their nests (Matsuura and Sakagami 1973),and also to prey on other social wasps (pers. obs.),although most species hunt individually, capturing andkilling individual foragers leaving their nests or at externalfood sources (Matsuura 1984; pers. obs.). However, somelarge species, notably Vespa mandarinia Smith, 1852 andVespa soror du Buysson, 1905, are capable of launchingcoordinated attacks on nests of honeybees and other socialwasps, killing off the majority of the adult occupants, andthen occupying the nest over a certain period of time, duringwhich workers shuttle back and forth, transporting thebrood to their own nest. The process is described in detailin Matsuura and Sakagami 1973, and generally speakingconsists of three distinct phases; namely the hunting phase,slaughter phase and occupation phase. In the huntingphase, the hornets attack individually, loitering around thenest entrance and catching individual workers of the targetspecies one by one, bringing each one back to the nestupon capture. During this period several workers from thesame colony may be present at the prey nest, but eachone hunts individually. The slaughter phase commenceswhen attackers from the same nest stop capturing preyindividually, but instead attack and kill the defendingworkers one after the other, biting and maiming them withtheir mandibles. This phase ranges in duration from lessthan an hour to over a day, depending on the number ofattacking hornets and the number of occupants in the targetnest as well as the intensity of their defence. When most

of the original occupants are killed or cease to defend thenest, the occupation phase begins, in which the attackersoccupy the nest over a period ranging from several hoursto two weeks, while the captured brood is transported asdescribed above. Some hornets remain in the occupiednest at night, and the entrance is now guarded againstintrusion by hornets from other colonies and other animals,including humans. While social wasps do not generallyattack people away from their nests, V. mandarinia and V.soror will guard an occupied nest as ferociously as theirown, and will attack and sting anyone who approaches thenest too closely (Matsuura and Sakagami 1973; pers. obs.).

Apart from V. mandarinia and V. soror, the only otherspecies known to occupy nests of honeybees are Vespaorientalis Linnaeus, 1761 (Matsuura and Sakagami 1973)and V. tropica (Burgett and Akratanakul 1982; Ritter andAkratanakul 2006; pers. obs. unpublished).

The observations reported above therefore represent avaluable record of a presumed group attack by V. ducalison the nest of another social wasp, leading up to theannihilation of the colony and occupation of the nest. Inclose to nine years of observing social wasps in Hong Kong,I have never encountered any nests of Vespa species beingattacked by V. ducalis. To the best of my knowledge, thereare also no published records of such attacks. While it isnot surprising that there have been no observations orreports on such behaviour, it is all the more interestingbecause V. ducalis is the species least likely to attack enmasse, due to its small colony size, its hunting habits andthe the manner by which it feeds its larvae (see below).

V. ducalis is unique among hornets in that it feeds its larvaeexclusively with regurgitated crop contents and never withanything solid (pers. obs.). In several observation coloniesI reared indoors, workers would ignore any whole insectspresented to them, and while they would accept items suchas the thoraxes of dragonflies or honeybees cut open toexpose the flesh, the wasps would chew on them for aperiod of time, but would then drop them, and did not feedanything to the larvae at all. Through long periods of timespent watching my observation colonies as well as thosein the wild, it was also apparent that workers returning tothe nest never carried any solid food or fed any visibleobject to the larvae, but instead would return with theirgasters distended by the engorged crop and feed the larvaethrough regurgitation. This is in contrast with V. tropica,which is recorded to have similar predatory habitsthroughout its range, although it is known to attack andoccupy nests of honeybees en masse in tropical regionssuch as Thailand and Singapore (Burgett and Akratanakul1982; Ritter and Akratanakul 2006; pers. obs. unpublished).Although V. tropica appears to prey exclusively on polistinewasps in Hong Kong, imbibing the body fluids of polistinewasp immatures and feeding its own larvae byregurgitation, workers in observation colonies rearedindoors by the author readily took prey such as the thoracic



flesh of dragonflies, crickets and even pieces of prawnmeat, and fed these to the larvae after 30 to 120 secondsof mastication. Thus the aspect of the hunting phase inthis instance is highly puzzling. It seems unlikely that thegathering of attackers from the same colony leading up tothe slaughter and occupation could have developed withoutthe hunting phase. However, while it is perfectlyconceivable that V. tropica could first begin huntinghoneybees or other wasps at their nests independently ofeach other before proceeding to the slaughter phase onceenough individuals from the same nest are present, it ishighly unlikely for V. ducalis to do the same. Since V. ducalisfeeds its larvae only on liquid crop contents obtained fromthe larvae and pupae of other wasps, and unlike otherhornets does not feed the flesh of insects to its larvae, it ishighly unlikely that it would hunt honeybees or other waspssince the solid flesh would be useless to it.

Since I did not witness the original attack, I have consideredthe possibility that the V. bicolor nest was first attacked byanother species such as V. soror or V. tropica. However,this is unlikely for three reasons. Firstly, it does not makesense that another species such as V. soror or V. tropicaattacked and gained occupation of the V. bicolor nest onlyto have V. ducalis take over and take the prey forthemselves; if another species were to have attacked andoccupied the nest they would have remained in the nesttill they consumed all the brood, and there would be nothingleft in the empty nest which would warrant subsequentoccupation by V. ducalis to obtain. Secondly, while I havealso considered the possibility that the nest could havefirst been attacked and occupied by another species, whichin turn was driven away by V. ducalis, this is also highlyunlikely due to the fact that among the six common Vespaspecies in Hong Kong V. ducalis is always at the lowestlevel of the dominance hierarchy at external food sourcessuch as fallen fruit and tree sap in Hong Kong (pers. obs.)and this also holds true in Japan, where it is the leastdominant among five common species at sources of treesap (Matsuura 1984). From numerous personalobservations it is often chased away by workers of otherVespa species, and is always at the losing end of anyphysical combat. As hornets guard conquered nests fiercelyduring the occupation phase, it is unlikely that V. ducaliswould be able to enter and take over a nest guarded byeither V. soror or V. tropica. One might argue that if V.ducalis is presumed capable of overpowering a V. bicolorcolony, it should also be able to take over a colony occupiedby another species, but with V. bicolor being the smallestlocal hornet species, the size difference between the twospecies would make it far easier and more likely forindividuals of V. ducalis workers to overpower V. bicolorthan to overpower either V. soror or V. tropica. At foodsources such as fallen fruit or tree sap, individuals of V.ducalis sustain no damage in combat with V. bicolor, whichoften gives up attempting to drive them away if they persistin attempting to feed from the same fruit or tree, but areoften injured by V. soror and even V. tropica under similar

circumstances (pers. obs.). Lastly, hornets generally forageindividually; even in species like V. mandarinia or V. soror,they work independently of each other before the slaughterphase begins. If another species had first attacked the V.bicolor nest and taken the prepupae, pupae and largelarvae, it is possible that a single individual of V. ducaliscould find the nest and take the remaining small larvae,but it is highly unlikely that more individuals would berecruited to occupy and guard a nest with such a smallremaining amount of prey inside. Therefore, although Icannot prove that V. ducalis was responsible for the originalattack which led to the demise of the colony due to a lackof direct observations, these three reasons suggest thatthe group of V. ducalis were indeed the original attackersand not opportunists moving in only after another speciesfirst invaded the prey nest.

It should be noted that according to my personalobservations covering the same localities over seven years,foraging individuals and nests of V. ducalis were atypicallyabundant in 2009. Therefore, there is a possibility that theneed for food could not be met by polistine nests alone,triggering the wasps to attack vespine wasps instead. Dueto the fact that vespine wasps are far more capable ofdefending their nests against another Vespa species, anindividual V. ducalis would not have been able to invadethe V. bicolor nest and gain access to the brood, thusnecessitating several individuals to invade and overpowerthe original occupants.

Besides this particular incident, I observed a single workerof V. ducalis circling and landing on a nest of V. bicolorbuilt in a small tree in September 2010. It did not attemptto attack or capture any of the V. bicolor workers, butinstead landed and walked on the envelope as well as thebranches surrounding the nest, taking flight and circlingfor brief periods before landing and walking again.Occasionally it was attacked and brought to the ground bythe V. bicolor workers, which at one point became quiteagitated, resulting in a group of 15 to 20 rushing about theenvelope and preventing the V. ducalis worker from landing.The intruder appeared to suffer no damage from theseattacks. The circling, landing and walking continued fornearly 45 minutes before the wasp flew off and did notreturn. Unfortunately I did not find out the result of thisbehaviour because the nest was destroyed by people thenext day. Given that the V. ducalis individual in questionshowed a distinct interest in the V. bicolor nest, yet madeno attempt to attack or capture any of the workers, it isplausible that V. ducalis bypasses the hunting phase andinstead, by flying near and walking on the nest envelopeor nearby objects, possibly leaves chemical trails whichother individuals from the same colony pick up, enteringdirectly into the slaughter phase. This remains an openquestion and further observations are certainly welcome.

J. X.Q Lee 18


ACKNOWLEDGEMENTS

I would like to thank Christophe Barthélémy and Graham Reels fortheir skilled editing, constructive criticism and advice on this article. Ialso thank Chan Kam Wah for invaluable assistance in observing V.ducalis throughout 2009.

REFERENCES

Archer, M. E. 1991. Taxonomy and bionomics of the Vespatropica group (Hymenoptera, Vespinae). Entomologist’sMonthly Magazine 127: 225 -232.

Burgett, M. and Akratanakul, P. 1982. Predation on theWestern Honey Bee, Apis mellifera L., by the Hornet, Vespatropica (L.). Psyche 89: 347 – 350.

Lee, J. X. Q. 2009. Potentially Dangerous Bees and Waspsof Hong Kong. Hong Kong Entomological Society PopularEntomology Book Series #2. 126pp.

Matsuura, M. 1984. Comparative biology of the fiveJapanese species of the genus Vespa (Hymenoptera,Vespidae). Bulletin of the Faculty of Agriculture, MieUniversity, 69: 1 – 131.

Matsuura, M. 1991. Vespa and Provespa. In: The SocialBiology of Wasps (Ross, K.G. and Matthews, R. W. eds.).Cornell University Press. 678pp.

Matsuura, M. and Sakagami, S. 1973. A bionomic sketchof the giant hornet, Vespa mandarinia, a serious pest forJapanese apiculture. Journal of the Faculty of Science,Hokkaido University, Series VI. Zoology, 19(1): 12 – 162.

Matsuura, M. and Yamane, Sk. 1984. Biology of theVespine wasps. Hokkaido University Press, Sapporo.429pp.

Ritter, W. and Akratanakul, P. 2006. Honey bee diseasesand pests: a practical guide. FAO Agricultural and FoodEngineering, Technical Report 4.

FIGURES

Figure 1: Individuals of V. ducalis at the occupied nestof V. bicolor.

Figure 2 & 3: Individuals of V. ducalis feeding on thelarvae before returning to their own nest.



Figure 4 & 5: Other individuals not feeding on the larvaebut lingering around the occupied nest

Figure 6: A worker visibly agitated after the envelopewas removed to facilitate observation


Observations on the luminescence configurations of eight firefly genera and their immature stages

Vor Yiu31E, Tin Sam Tsuen, Kam Sheung Road, Yuen Long, N.T., Hong Kong

email: [email protected]

Luminescence of eight firefly genera 20

ABSTRACT

Long exposure photography was used for recordingluminescence configuration of eight firefly genera in HongKong, namely: Rhagophthalmus, Stenocladius,Lamprigera, Pyrocoelia, Diaphanes, Aquatica, Luciola andPteroptyx, all sampled in Hong Kong. It was found thatluminescence configuration does not necessarily coincidewith light organ configuration of the same firefly.Additionally, a large portion of the fireflies in this study arecapable of displaying bipartite light spots from their obroundor rectangular light organs. Stenocladius can display threedifferent types of luminescence configurations, includingdiffused light from the whole body. This study also showsthat male and female adult of Lamprigera retain their larvallight organs while other species develop additional lightorgans with their larval light organs remaining intact.Possible implications of the luminescence configurationsare proposed and discussed.

Keywords: Fireflies, bioluminescence, Lampyridae,Rhagophthalmidae, aposematic, light organs, Hong Kong.

INTRODUCTION

Fireflies are the best known animals displayingbioluminescence. The light emitting part of a firefly body iscalled lantern, luminescent organ, photic organ or lightorgan. Light organs of fireflies often appear as conspicuouswhite patches on preserved specimens. However, for somespecies, the light organs are not conspicuous or even notvisible externally. In some cases, the light produced is verydim or only lasts for a short period of time during thedevelopment from larva to adult. As a result, they couldsometimes be overlooked. In this study, long exposurephotography was used to record the luminescenceconfiguration of fireflies.

MATERIALS AND METHODS

As the light emitted by fireflies is very dim, special camerasettings were required to clearly show the light. To increaseexposure of the firefly luminescence to the camera sensor,long exposure time (from 1/8 sec. to 120 sec., dependingon species) was used, with a tripod. In many cases, sensorsensitivity would be adjusted to a higher value (ISO 400 toISO 3200), and/or large lens aperture would be selected.Although the glowing light organs are shown, the otherparts of the body are not exposed to light when the fireflyis in the dark. Consequently, in order to show the wholebody and therefore the relative positions of the glowinglight organs, two methods were used in this study: 1. As

soon as the long exposure photo was taken, another photowith flash light was produced, so that the relative positionof the light organs could be seen by comparing the twophotos; 2. using fill-in light. This was done by either pointinga torch towards the objects nearby, allowing the reflectedlight to shine onto the firefly, or simply using fill-in flashlight from the camera system. The intensity of fill-in lightwas controlled such that it would not overshadow the lightemitted by the light organs. All photos were taken with eitheran Olympus E3 digital camera connected to a Zuiko DigitalED 50 mm f/2.0 Macro lens, or an Olympus E620 digitalcamera connected to the same lens, or a Canon 550Ddigital camera connected to a EFS 60 mm f/2.8 MacroUSM lens or to a MP-E65 mm f/2.8 1-5X macro lens.

The study involved 10 species of fireflies belonging to eightgenera, collected from 2006 to 2010 in Hong Kong , China,namely:1. Rhagophthalmus motschulskyi and Rhagophthalmus sp.(Rhagophthalmidae). Two females of Rhagophthalmusmotschulskyi were seen glowing in the wild and in captivityrespectively, and long exposure photos were taken at themoment when they glowed. The identity of the female wasinferred from another female with the same morphologicalfeatures found in the same locality, which mated with anidentified male of R. motschulskyi. A pair of unknownRhagophthalmus sp. were found mating in the wild andwere collected. The female was observed and a series oflong exposure photos was taken during oviposition.

2. Stenocladius spp. (Lampyridae: Ototretadrilina-Ototretinae complex). More than 50 females wereobserved in about 20 night trips in three different wellvegetated localities in Hong Kong, from November, 2009to January, 2010, and from November 2010 to December,2010. Long exposure photos were taken to show theluminescence configurations of eight different femaleindividuals in the wild. Two females were collected forintensive observation and for taking long exposure photosin an indoor environment. A light emitting male of aStenocladius sp. found on a spider web was collected andlong exposure photos were taken during the short momentwhen it emitted light. A Stenocladius sp. larva was collectedin the wild and reared; long exposure photos were takenwhen it glowed. Because of the very different markings oftwo types of larvae found (another one without longexposure photo taken), it could be inferred that there aretwo different species of Stenocladius in Hong Kong.Therefore, it is possible that the females and malesmentioned in this study belong to different species. Fromtheir distinct external morphology, there is no doubt thatthey belong to this genus. Two events of attempted mating

21 Luminescence of eight firefly genera


were observed in the wild, which gave support to theassociation between the male and the female.

3. Lamprigera sp. (Lampyridae: Lampyrinae)A female larva of an unknown Lamprigera was collectedin the wild and reared; it pupated but died beforeemergence of the adult. Long exposure photos were takenwhen light was emitted from the larva and from the pupa.Another female and a male of the same unknownLamprigera were seen glowing in the wild and longexposure photos were taken. All the individuals mentionedabove were found in a very restricted locality on Tai MoShan.

4. Pyrocoelia sp. (Lampyridae: Lampyrinae)A female larva of an unknown Pyrocoelia sp. was collectedin the wild and reared. It was observed intensively and aseries of long exposure photos were taken in the courseof its development from pre-pupa to adult. Another femaleand several males of the same Pyrocoelia sp. were seenglowing in the wild and long exposure photos were taken.

5. Diaphanes citrinus (Lampyridae: Lampyrinae)A male adult was collected and series of long exposurephotos were taken in an indoor environment. Another maleadult was seen glowing in the wild and a series of longexposure photos were taken.

6. Aquatica cf. ficta (Lampyridae: Luciolinae)A female pupa was obtained in February, 2011, by rearinglarvae. A series of long exposure photos were taken in thecourse of its development into an adult.

7. Luciola terminalis (Lampyridae: Luciolinae)A male adult was collected in the wild and kept in atransparent plastic vial. An AVI format (30 frames persecond) video (duration: 1min. 24 sec.) was taken when itemitted light. The video was taken with an Olympus EPL1digital camera connected to a Zuiko Digital ED 50 mm f/2.0 Macro lens. The video was played frame by frame tosee the changes in the luminescence pattern.

8. Pteroptyx sp. (Lampyridae: Luciolinae)A female pre-pupa of Pteroptyx sp. was obtained inOctober, 2010, by rearing larvae. A series of long exposurephotos were taken when it glowed during larvaldevelopment. A male adult was collected in the wild andkept in a transparent plastic vial. An AVI format (30 framesper second) video (duration: 45 sec.) was taken when itemitted light. The video was taken with the same cameraand lens mentioned above. The video was played frameby frame to see the changes in the luminescence pattern.

The numbering of abdominal segments and ventrites refersto the true segments.In some cases, light is emitted from the light organs locatedjust beneath the ventrites, but in other cases, especially inimmature stages, light is emitted from somewhere inside

the abdominal segment or from a whole abdominalsegment. They are termed differently in the results section.

Abbreviation: V= Abdominal ventrite

RESULTS

1. Rhagophthalmus motschulskyi and Rhagophthalmus sp.Two different luminescence configurations were observedon adult female specimens. The first one was a large lightspot that appeared on V8 (Fig. 1.1, 1.2). The second onewas during oviposition, a bright light spot appeared nearthe right posterolateral margin of mesothorax, metathorax,and 1st-9th abdominal segment (presumably there arecorresponding light spots at the opposite side, but theyare not shown in the photo records). An additional lightspot appeared near the posterodorsal margin of each ofthe 11 segments mentioned above. The lateral light spotson each of the abdominal segments were glowing duringobservation, but the lateral light spots on the two thoracicsegments as well as the dorsal light spots were sometimesnot emitting light (Fig. 1.3-1.6). No well-defined light organswere seen in the preserved specimens.

2. Stenocladius spp.The larva displays one pair of light spots was evident onthe 7th and 8th abdominal segments (Fig. 2.1). Threedifferent patterns of luminescence were observed on adultfemale specimens. The whole body, except the anteriorpart of pronotum and the head, glowed evenly (Fig. 2.2)and this was the most common pattern observed. Lessfrequently, the whole body, except the anterior part of thepronotum and the head, glowed evenly, and at the sametime a pair of large, brighter light spots appeared on the8th abdominal segment (Fig. 2.4). Finally, a pair of largelight spots appeared on the 8th abdominal segment andat the same time the whole body glowed very weakly, therewas also a pair of tiny light spots close to the leftposterolateral margin of abdominal segment 2-4(presumably, the same pairs could be seen on the rightside of the body, but is not shown in the photos). It appearedthat tiny light spots also appeared in the metathorax, butthey were not definitely shown in the photos (Fig. 2.5).Adult males seldom emit light, and only two instances wereobserved amongst about 20 individuals in the wild; bothwere caught in spider webs. A pair of weak light spotsappeared on V6 (Fig. 2.6). No well defined light organsare seen in the preserved specimens.

3. Lamprigera sp.The larva displayed one pair of “C”-shaped light spots onV8 (Fig. 3.1), which were also shown by the female pupaand adult. The male adult showed one pair of light spotson V8 (Fig. 3.4).

4. Pyrocoelia sp.The larva displayed one pair of large light spots on theeighth abdominal segment (Fig. 4.1) which was the same

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for the female prepupa and pupa (Fig. 4.2, 4.3 ). On thelast day before emergence, an additional pair of small lightspots appeared on V6 (Fig. 4.4). In the adult female, anadditional pair of larger spots appeared on V7 on thesecond day after emergence. All three spots glowedsimultaneously (Fig. 4.5). The light spots at the eighthabdominal segment gradually dimmed and finallydisappeared on the fourth day after emergence (Fig. 4.6).In the adult male there was an obround light spot on V6and V7 (Fig. 4.7). When the intensity of light given out waslow, it appeared as 2 spots at both end of the obround lightorgans (Fig. 4.8).

5. Diaphanes citrinusThe male adult emitted light on V6 and V7, sometimes inan obround shape (Fig. 5.1), but when the intensity of lightemitted was low, it appeared as 2 spots at both end of theobround light organs (Fig. 5.2).

6. Aquatica cf. fictaGlowing larvae under water were occasionally seen, butno long exposure photo was successfully taken to showthis. Clearly defined light organs could be seen as a pairof spots on the eighth abdominal segment (Fig. 6.1) On afive days old pupa a pair of light spots appeared on theeighth abdominal segment and a pair on V6 (Fig. 6.2).When the same pupa was 8-day old (two days beforeemergence), the light spots on V6 became obround shaped(Fig. 6.3). When the intensity of light emitted was low, thetwo extremes of the stripe were brighter (Fig. 6.4). Thelight spots on the eighth abdominal segment diminishedas the pupa became more mature. On the first day afteremergence of an adult female, the same obround lightspots appeared on V6. When the intensity of light emittedwas low, it appeared as two-spotted form (Fig. 6.5). Onthe third day after emergence, the light spots on the eightabdominal segment became very small (Fig. 6.6) anddisappeared on the fifth day after emergence (Fig. 6.7).The light source on V6 appeared as two spots when it wasnot glowing fully (Fig. 6.8). No flashing (only intermittentglow) was observed until the twelfth day after emergence.

7. Luciola terminalisThe male adult emitted light from V7. It was continuousand steady throughout the recording period and was moreor less even across the whole surface of V7 except on theterminal portion. The light emitted from V6 was flashingand bipartite throughout the recording period (Fig. 7.1).The light organs on V6 and V7 are well defined whitepatches covering nearly the whole surface of V6 and V7(Fig. 7.2).

8. Pteroptyx sp.Larvae were occasionally seen glowing either in captivityor in the wild, but no long exposure photo was successfullytaken to show the glowing pattern. Two light organs couldbe seen on the eighth abdominal segment, although theywere not very well defined (Fig. 8.1). The prepupa displayed

two light spots on the eighth abdominal segment, whichcoincided with the light organs of the larva (Fig. 8.2). A twodays old female pupa displayed a pair of light spots on V8(Fig. 8.3). The last day before emergence (10-day oldpupa), an obround light organ was clearly visible on V6(Fig. 8.4). As soon as the pupa turned into an adult, lightwas emitted as two spots on V8 and evenly from the lightorgan on V6 (Fig. 8.5). No flashing was observed. In themale adult, a flashing light appeared either on V6 as a pairof spots with none on V7 (Fig. 8.6), or from both V6 andV7 as a bipartite structure (Fig. 8.7). Only when the lightorgans were glowing fully, did they appear as rectangularstructures (Fig. 8.8). The light organs beneath V6 and V7were well defined white patches covering nearly the wholesurface of these ventrites (Fig. 8.9), leaving only the medianposterior projection of V7.

DISCUSSION

From the results, it is shown that long exposurephotography with a single macro lens reflex camera canbe a useful tool to record the luminescence configurationof fireflies, which does not always coincide with theconfiguration of light organs of the same firefly. In this study,light organs of Rhagophthalmus and Stenocladius are evennot visible in both dry specimens and specimens preservedin alcohol.

All members of the Lampyridae observed in this study andin both sexes, are capable of displaying bipartite light spotsfrom their obround or rectangular light organs (Pyrocoelia,Diaphanes, Pteroptyx); in the genus Lamprigera, the lightorgan is already bipartite. Therefore, the obround orrectangular light organ may be regarded as a combinationof two enlarged spot light organs in an abdominal segment,rather than being two distinct structures. All larvae andlarviform females involved in this study had two spottedlight. This two spotted configuration could be explained bytheir proximity to the two spiracles of each abdominalsegment, which supply oxygen necessary for thebioluminescence’s chemical reaction; or the result ofuneven innervation. In males the enlargement of the twospotted light organs merging into an obround light organmay well be the result of competition for females bydisplaying larger light patch(s). It is interesting to note thatin Lamprigera, both the adult male and female retain thetwo spotted pattern on V8 of their larval stage, butPyrocoelia and Diaphanes, while members of the samefamily, change their light organs to V6 and V7. Closeexamination of the specimens showed that in order to makeroom for the genitalia, there was no fat deposited insegment eight of Pyrocoelia and Diaphanes (both sexes).Although segment eight of Lamprigera is not substantiallylarger, a considerable amount of fat is deposited in thissegment and the preceeding one which showed no light.In Pyrocoelia, Aquatica and Pteroptyx, adult femalesdeveloped their light organs when their larval light organson V8 were still intact and functioning. Therefore the light


organs of the adults of these three species are not directlyderived from their larval stage.

Luminescence configuration of Stenocladius is exceptionalin that it is not localised as spots. Buck (1948) suggestedthat photogenic cells were typically grouped together inone or more compact localised masses with specifictracheal and nervous supplies; and regarded the lightemitted in Phengodes, which is produced by looseindependent giant cells, apparently without tracheae, asexceptional. The light produced by Stenocladius is moreevenly distributed and the light producing mechanism maypossibly be even more loosely organised than that ofPhengodes. Chen (2003) reported that the prepupa (sexnot mentioned) and the male pupa of Stenocladiusbicoloripes in Taiwan produced diffused light and the larvaeof Stenocladius do not have such diffused luminescence.Adult females of Stenocladius gain the ability of producingspot light as larvae, as is in many other fireflies, thereforewhat would be the reason for having additional diffusedluminescence? Males have well developed antennae usedin sexual interaction, therefore communication betweenthe two sexes may not solely rely on light signals andchemical signaling may also play an important role. In viewof their soft body surface and low mobility, aposematicdisplay may be an explanation to added luminescence.Many fireflies were found to be able to produce unpalatableor toxic substances (Blum and Sannasi, 1974; Eisner etal., 1978; Fu et al., 2009) and it has been proposed andtested that luminescence is an aposematic display in fireflylarvae (Buschman, 1988; De Cock, 2000; Fu et al., 2009,Sivinski, 1981). For the wingless and less mobile adultfemales of Pyrocoelia, Diaphanes and Lamprigera, theircomparatively very bright light organs may also play animportant role of aposematic display.

ACKNOWLEDGEMENTS

I am grateful to Xue-Yan Li, Kunming Institute of Zoology, China, andRaphäel De Cock, Evolutionary Ecology Group, University of Antwerp,Belgium, for reviewing the original manuscript and providing valuablecomments. I would also like to thank Graham Reels and ChristopheBarthélémy for their valuable advices to content of this paper.

REFERENCES

Blum M.S. & Sannasi A, 1974. Reflex bleeding in thelampyrid Photinus pyralis: defensive function. Journal ofInsect Physiology 20(3): 451-460.

Buck, J.B., 1948. The anatomy and physiology of the lightorgan in fireflies. Annals of the New York Academy ofSciences 49(3): 397-470.

Buschman L.L., 1988. Light Organs of Immature Fireflies(Coleoptera: Lampyridae) as Eye-Spot/False-Head Display.The Coleopterists Bulletin 42(1): 94-97.

Chen T.R., 2003. The Fireflies of Taiwan. Field ImagePublications. 255 pp. (In Chinese).

De Cock R. & Matthysen E., 2000. Aposematism andbioluminescence: experimental evidence from glow-wormlarvae (Coleoptera: Lampyridae). Evolutionary Ecology 13:619-639.

Eisner T., Wiemer D.F., Haynes L.W., Meinwald J., 1978.Lucibufagins: Defensive Steroids from the FirefliesPhotinus ignitus and P. marginellus (Coleoptera:Lampyridae). Proceedings of the National Academy ofSciences of the United States of America 75(2): 905-908.

Fu X.H., Meyer-Rochow V.B., Tyler J., Suzuki H., De CockR., 2009. Structure and function of the eversible organs ofseveral genera of larval firefly (Coleoptera: Lampyridae).Chemoecology 19:155-168.

Sivinski J., 1981. The Nature and Possible Functions ofLuminescence in Coleoptera Larvae. The ColeopteristsBulletin 35(2): 167-179.

FIGURES

Fig. 1.1. Rhagophthalmus motschulskyi adult female— Large lightspot on V8.

Fig. 1.2. Rhagophthalmus motschulskyi adult female— Large lightspot.



Fig. 1.3. Rhagophthalmus sp. adult female— luminescence duringoviposition.

Fig. 2.1. Stenocladius sp. larva — light spots on seventh and eighthabdominal segments.

Fig. 2.2. Stenocladius sp. adult female — diffused glow from thewhole body.

Fig. 2.3. Stenocladius sp. adult female — whole body under flashlight.

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Fig. 1.4. Rhagophthalmus sp. adult female— luminescence duringoviposition

Fig. 1.5. Rhagophthalmus sp. adult female — luminescence duringoviposition



Fig. 2.6. Stenocladius sp. adult male — light spots on V6.

Fig. 3.1. Lamprigera sp. larva — one pair of “C”-shaped light spotsonV8.

Fig. 3.2. Lamprigera sp. female pupa — one pair of “C”-shaped lightspots onV8.

Fig. 3.3. Lamprigera sp. adult female — 1 pair of “C”-shaped lightspots on V8.

Fig. 2.5. Stenocladius sp. adult female — light spots on the eighthabdominal segments, whole body glows weakly with tiny light spotson the second to fourth abdominal segments.

Fig. 2.4. Stenocladius sp. adult female — diffused glow from thewhole body with two spotted light on the eighth abdominal segment.


HKEB 3 (1) April 2011 © Hong Kong Entomological SocietyHKEB 3 (1) April 2011 © Hong Kong Entomological Society

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Fig. 4.2. Pyrocoelia sp. prepupa — one pair of large light spots onthe 8th abdominal segment.

Fig. 4.3. Pyrocoelia sp. Female pupa — one pair of large light spots

on the 8th abdominal segment (dorsal view).

Fig. 4.4. Pyrocoelia sp. female pupa (last day before emergence) —one pair of light spots on the 6th & 8th abdominal segments.

Fig. 4.5. Pyrocoelia sp. adult female (2-day old) — one pair of lightspots on the 6th, 7th & 8th abdominal segments.

Fig. 3.4. Lamprigera sp. adult male — 1 pair of light spots on V8.

Fig. 4.1. Pyrocoelia sp. larva — one pair of large light spots on the8th abdominal segment.

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Fig. 4.8. Pyrocoelia sp. adult male — 2-spotted light from theobround light organ on V6 & V7.

Fig. 5.1. Diaphanes citrinus adult male — obround light organ in fullglow on V6 & V7.

Fig. 5.2. Diaphanes citrinus adult male — 2-spotted light from theobround light organ on V6 & V7.

Fig. 6.1. Aquatica cf. ficta larva — light organ on the 8th abdominalsegment.

Fig. 4.7. Pyrocoelia sp. adult male — obround light organ in fullglow on V6 & V7.

Fig. 4.6. Pyrocoelia sp. adult female (4-day old) the light spots onethe 8th abdominal segment have disappeared.



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Fig. 6.4. Aquatica cf. ficta pupa (8-day old) — a pair of light spots onV8 and V6.

Fig. 6.6. Aquatica cf. ficta adult female (3-day old) — light spots onV8 diminished.

Fig. 6.7. Aquatica cf. ficta adult female (5-day old) — light spots onV8 have disappeared.

Fig. 6.2. Aquatica cf. ficta pupa (5-day old) — a pair of light spots on

V6 and V8.

Fig. 6.3. Aquatica cf. ficta pupa (8-day old) — a pair of light spots atV8, obround shaped light on V6.

Fig. 6.5. Aquatica cf. ficta adult female (1-day old) — a pair of lightspots on V6 and V8.

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Fig. 7.2. Luciola terminalis adult male — light organs on V6 and V7occupying the whole ventrite surface.

Fig. 8.1. Pteroptyx sp. larva — a pair of light spots on the 8th

abdominal segment.

Fig. 8.2. Pteroptyx sp. prepupa — a pair of light spots onthe 8th

abdominal segment.

Fig. 8.3. Pteroptyx sp. Pupa (2-day old) — a pair of light spots onthe 8th abdominal segment.

Fig. 7.1. Luciola terminalis adult male — partial light from V7 and 2-spotted light from V6.

Fig. 6.8. Aquatica cf. ficta adult female (3-day old) — 2-spotted lighton V6.



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Fig. 8.6. Pteroptyx sp. adult male — 2-spotted light from V6.

Fig. 8.7. Pteroptyx sp. adult male — 2-spotted light from V6 and 2-spotted light from V7.

Fig. 8.8. Pteroptyx sp. adult male — Light from V6 and V7 in fullglow.

Fig. 8.9. Pteroptyx sp. adult male — Light organs on V6 and V7.

Fig. 8.4. Pteroptyx sp. Pupa (10-day old, last day before emergence)— a pair of light spots on the 8th abdominal segment & obround lightorgan on V6.

Fig. 8.5. Pteroptyx sp. adult female (1-day old) trapped in pupal case— 2-spotted light from V8 and obround shaped light from V6.

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