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THE FRUIT FLIES OF NEW YORK

By F. L. GAMBREI.I..NroJ York Sta te Agricultural Expfrime.¡t Statio7l. Ge7let'il,N. Y.:

ABSTRACT

The economic spedes oí íruit fiies in :'\ew York indudes: The cherry Cruit.flies,Rhagoletis fausta and R. cingulata; the apple maggot, R. pom,mella; the walnut huskmaggot, R. S1fatlÍs: and the currant íruit tlr. Epochra canadc7lsis. Certain pointsrelative to the distrihution. abundan.'e. liie history. and ('olltrol of these species are"discussed ,

In the group of fruit fiies (Trypetidae) there are records of thirty- '.seven speciesand four varieties whichare known to occur in the state of:SNew York. Of this number there can be listed, at most, only fivespecies which prove to be of economic importanci! to the horticultura! ~

industry. However this paper only ca1lsattention to certain interestinipoints which have been obtained in a study of the economic species.",Four of these belong to the Genus Rhagoletis and the other to the GenusEpochra. These are: the cherry fruit fiies, R. cingulata and R. fausta;.;,,"'"the apple maggot, R. pomonella, and a physiological species of the latter'''twhich attacks blueberries; the walnut husk maggot, R. suavis; and th~';:currant fruit fiy, Epochra canadensis. .!S'i

In view of the fact that New York is one of the important horti.ii .

cultural states it is only proper to call attention to the fact that certainrJspecies of fruit fiies occupy an important role in this particular industry~.,Without question the cherry fruit flies and the apple maggot are the t;WO.,most important economic species under consideration. The cherry in.t1

dustry of the state is represented by approximately 1,500,000 treeSojf~bearing age. The yield in 1930 as based upon the pack of canned and~'4'

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February, '31] GA!o{BRELL:FRUIT FUES OF NEW YORK 2Z7

froZeI1fruit amounted to 21,185 tons; and figuring this production atthe rate oí five cents per pound, which 15about the average price paid bycanners, the value oí the cherry crop on this basis was $2,117,500. Thisfigure does not take into consideration that part oí the crop which wassold as fresh fruit upon the local markets. The cherry fruit flies are animportant problem thruout the state wherever cherries are grown on acoromercial scale, and where control measures are not properly and effec-tively applied this pest oíten materia11y affects the quality and valueof the crop. Conv.ersely, those growers who adhere to a regular sprayprogram such as that recommended by the Spray Service seldom en-counter serious difficulty in producing fruit oí a quality which complieswitb the standards íonnulated by the íederal authorities and maintained

.. by the canning industry, as has been repeatedly shown both from thecommercial and experimental standpoint.

The production oí apples, which is another important íruit crop oí thestate, according to infonnation published by the U. S. Census Bureau in1925, showed a yield of 19,055,965 bushels in 1924. While the applemaggot is neither considered a major pest in all of the apple growing

~;¡;..areas of the state nor is it, generaUy speaking, the most important in-sect enemy of the crop, serious injury does occur in certain localities and,consequentIy. it assumes' an economic role in those areas. It 15oí interestto note that the presence oí apple maggot in fruit grown in the eastem

~I Vnited States has been sufficient within the past few years to attract.attention upon certain foreign markets, with the result that deftnite

Itaction has been taken to minimize the possibility oí introduction andestablishment of this insect in those countries. Need1ess to say, theState of New York is not immune from the standpoint oí maggot-free'fruit. According to Dr. P. J. Chapman, a member oí the EntomologyDivision oí the New York State Agricultural Experiment Station, who is

" .oonducting an exh8.ustive study of this insect in the Champlain and Hud-~son River sections, experimental work has shown that the flies are sus-'ceptihle to applications of arsenica1s to much the same degree as hasr.~pointed out by Glasgowand Gambre11,among others, in the case 0('. 'the cherry fruit flies (2). Experimental work seems to indicate that¡ cptOperlytimed and thoroly applied treatments oí arsenicals will affordI t goodcontrol against these insects. In conjunction with the spray pro-

gram maintained against these and other pests there is introduced, how-'ever, the problem oí spray residues which is another importaD.t consider-[ation.

" ,The walnut husk maggot, R. suavis, while not as important as the pre-. '. 'teding speciesunder New York conditions, is also worthy of mention.f~ ~.; t BIBLIOTECA

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228 (Vol. 24 "JOURNAL OF ECONOMIC ENTOMOLOGY -Wbile the production of nuts is not on such an extensive scale as are. cherries and apples, the marketing of the native b1ackwalnut is decided-,Iy on the decrease, which is perhaps due in some measure to deforest-.';1¡ation practices. In an effort to counteract this situation the b1ack wal-'..~nut has been supplantOO by the English (persian) walnut to some ex-/Itent, of which there are an increasing number of plantings in the state.' '"

These plantings are more or less limitOO to the northwestern tier ofcounties and west of the Cayuga Lake basin, particularly in the regíon of ....the Ontario plains and the Niagara peninsula. The walnut husk maggot'""occurs tbruout this regíon and attacks both wildand cu1tivatedwalnuts. ..

In some instances as much as eighty to ninety per cent of the nuts are ~infestOO. ..,::

DISTRIBUTIONANOABUNOANCE.Generally speaking, the presence ofthese species is associated with the appearance of the various fruits andnuts' but they present important problems only in certain rather re- 11

stricted areas. In Figure 12 are shown the various physiographic areas ';;,.,,r,'of New York and these conform in a generalway to the areas of greatest A"

abundance, distribution, and importance of the various species. It also.illustrates the principal horticultural areas. . i;;¡

While the apple maggot is rather generally distributed in ~ew Yorkand occurs to some extent in the Central Lakes and Great Lakes regíons,it is much more abundant and causes considerably greater losses in theChamplain area and Hudson River valley than in any other sectionsof ."' ,the state. Likewise, the cherry fruit fiiesoccurin all the cherry growing.~ "'-.

areas, but in contrast to the apple maggot are of about equal importance .~~;:in the Great Lakes, Central Lakes, and the HudSOJ!Valley regíons and;appear to develop equally as well in each locality. As has been pre- ('viously notOO, the walnut husk maggot has been observOOprincipaUYr,thruout central and western New York, but is also known to occur in theHudson valley. According to records thus far the currant fruit By has.;~,~"

been found in the northeastern part of the state along the Champlain}ivalley, and may possibly occur in some other sections. The bluebenyimaggot, which is a physiologícal strain or species of the apple °maggot,J'occurs on Long Island, but thus far the writer has observOOthis species .neither in the Adirondack mountains regíon nor in westem New York. '"

COMPARISONOF LIFE HAB1TSANOCONTROL. A detailOO discussion ofl

the life history and control of any one of these species requires more dis-~.;;"cussion than space permits here. The cherry fruit By studies, carried on'Ji.~~:i:~under the direction of Dr. Hugh Glasgow and assisted by the writer, andt.:;~the apple maggot problem which is being extensively investigated by'~'

February, '311 GAMBRELL: FRUIT FLIES OF NEW YORK 229

Dr. P. J. Chapman in the Champlain and Hudson valleys, wi11be thesubjects of publications by the New York State Agricultura! ExperimentStation in the nea.r future and need not be e1aborated upon at this time.However, there are three points to which the writer desires to ca1latten-tion. First: The apple maggot, even tho it occasionally feeds upon blue-berries and plums, is in the main monophagous in its feeding habits; thecherry fruit flies thus far have onIy been rea.red from the cultivated

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FIG. 12.-Physiographic areas, horticultural regions and distribution of fruit

fii~ of economic importance in New York.

cherry and are apparently monophagous species; the walnut husk mag-got, while probably not entirely a monophagous species, has onIy beenrea.red from four species oí nuts, all of which belong to the Genus Juglans.Second: A11of these species are, in the main, single brooded. Third: A11oí these species are susceptible to arsenicals and do not appea.r to beattracted to bait traps. These points are all in striking contrast to suchspecies as the Mediterranean fruit fiy, the Mexican orange maggot, andothers which are polyphagous in feeding habits, multi-brooded, and areattracted to bait traps.

WALNUTHUSK MAGGOT.The writer for the past few years has beeninterested in that phase of the fruit fiy study which deals with the wal-

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230 JOURNAL OF ECONOIolICENTOMOLOGY IV01.24

nut husk-maggot (R. suavis), its life history and control, phylogeneticrelationship, susceptibility to arsenicals, and similarity of habits to theother species oí the group. R. suavis completa, a subspecies oí R. suavis

and R. juglal1dis, have recentIy been observed in the nut growing ,.

area oí California and threaten to become important insect pests of .English walnuts there (3, -l. .')). The discussion relative to this species(sua;'is) is inc1uded here to summarize the iníormation as obtained '"under :'\ew York conditions.

The walnut husk-maggot attacks butternuts, black, English, andJapanese walnuts on which the larvae feed within the exocarp or hull oíthe nut. The eggs are deposited during August beneatb tbe surface ofthe huII, and number from a very few to one hundred or more in a singlepuncture. There is usually but one puncture to a nut, but occasionalIytwo are observed. Injury by the walnut husk maggot manifests itse1fin tbree difierent ways: first, in impairing the quality of tbe kernel witbinthe shell; second, in causing the husk or exocarp to stick to tbe shell; andthird, in a blackening of the shells which makes tbem unattractive.Some of the nuts which become infested early in tbe season fa1l pre-maturely, while others remain on the trees long after normal nuts havefallen from thc husks to the ground. In some instances where nuts areattacked when still premature the shell becomes soft and the entire ker-nel may be destroyed by the maggots or rendered worthless by the attackof fungi

Injury is first detected by the presence of an egg puncture as a small,black, circular spot from which exudes a sap that adheres to the surfaceof the nut and upon drying appears as greyish-br<)wn to black, irregular.discolored areas (Plate 8). In feeding the larvae tunnel their way tbruthe exocarp and as they approach maturity work their way towards tbeouter surface oí the husk, at which time the nuts show several small,brown to black, water-soaked spots, or a few well defined, large <lis-colored areas. Tbe larvae issue from the husks from about Septemberfirst to November first, and pupate witbin the soil at depths of from one-half to one and one-half inches, in which condition they remain until tbefollowing summer. Tbe flies usualIy begin to emerge about JuIy 15 andcontinue until the middle of August. Tbe life history of this and tbeother species, as based upon the emergence of fIies,is shown in Figure 13.

Whilé the degree of control of the walnut husk maggot has not been asstriking in some respects as that obtained against the cherry maggots,this study reveals the fact that the flies are susceptible to applications ofarsenicals. Tbe efforts relative to control have been somewhat limitedowing to the small number of trees available for experimental work, but

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Plate S

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Injury of the \\'alnut husk maggot (Rhagoll'lis s//ll¡Ú) on butternut. Upper left: eggpuncture and Ruid \\'hil'h has exuded from the husk; remaining nuts show diffeI"'entstages of injury.

February, '31] GAMBRELL: FRtilT FLtES OF NEW YORK 231

the control obtained under such conditions compares favorably withthat secured against the cherry maggots under similar circumstances.Two applications of dry-mix or lime-sulfur and arsenate of lead, thefirst one made from ten days 10 two weeks after the initial emergence of ..

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June' JulyJ' b lb 21, Aug. 5FIG. n. Showing' ,Iailv temperature and emergen,'e of fruit fiie::>.

fijes, and the second from one week to ten days later, have given upwardsof ninety per cent control. As in the case of cherry fruit flies, in smallplantings or individual trees which are in close proximity 10 untreatedtrees, there is a migration of fiies between such trees which exerts a

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-232 ..JOURNAL OF ECONOMIC ENTO~IOLOGY [Vol. 24

marked influence upon the control obtained. Generally speaking, the ,,;flies are susceptible to treatments of arsenicals, and in the case of com.'

mercial plantings or trees which are some distance froro untreated treesglittle difficulty should be encountered in securing satisfactory control.¡¡¡

LITERA TURE CITED.

l. BRooKs, F. E. The Walnut Husk Maggot. U. S. D. A. Bul. 992. 1921.

2. GL.-\SGOW,H., and GA:IIBRELL,F. L. The Cherry Fruit Fly. Cir.87, N. Y. Agr.Exp. Sta. 1925.

3. BOYCE,A. 1\'1. The Walnut Husk Fly (Rhagoletis juglandis Cresson). Jour. Econ.Ent. Vol. 22, No. 6. 1929..'

4. KEIFER. H. H. Synopsis of the Dipterous Larvae Found in California Fruits.Mo. Bul. Calif. Dept. of Agr., Vol. XIX, No. 8. 1930.

[,. BOYCE.A. M. Control of the Walnut Husk Fly in 1929. Diamond Walnut News.Vol. XII, No. 3, pp. 14-lti. 1930.

INSECTICIDE INVESTIGATIONS DURlNG 1930 .,By E. P. FELT and S. W. BROMLEY,Bartlett Trt'e Research Laboratories,

Stamford, Connectú:ulABSTRACT

Molasses nicotine soap sprays, which have proven effective in the control of certain '<1delicate insects, were applied with safety to a series of thirteen species of trees at amolasses dilution of 1-20. Tulip and gray birch showed slight injury at this dilution.Due lO the dry seasons of the past two years, the chinch bug, Blissus leucoptems Saybecame a serious lawn pest in certain localities. A s<.'Tiesof sprays and dusts were ,¡¡testcd ior its control, with potassium oleate plus nicotine appearing the most promis-ing. A series of sprays were tested for the control of the rhododendron lace bug.Stephanilis rhododendri How., with results indicating the value of the spray whenthere was a thorough wetting oi the insecto Dormant <;>ilsprays \Veredemonstrated '.1

as effcetively controlling oak lcai rollers, Argyrotoxa se;nipurpurana Kf.. by killing ,the overwintering eggs. The tulip tree seale, Toumeyella lirüxkndr¡ Gmel., was I!

etfectively controlled by certain dormant oil sprays. but only partial control s were ,obtained after foliation had taken place and the seale had advanced in growth and ".4Jresistance. Field tests with dormant oils on sugar maples and black walnut demo~- ~strated the injurious effects of such sprays on these trees. Spray injury tests with 011.

and lime sulfur on foliage of various trees revealed a certain type of injury character- . :,istic of this combination. while combinations of soap and arsenate of lead on conifers ~also produced a characteristic type of injury. :1

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Every year brings innovations in the control of insects. New problemsarise with the advent of new insect pests. while control measures forsome'of the old established pests are not in all cases the most satis-factory which it is possible to devise. Experimentation is continuallybringing forth new methods, and the ever increasing number of ile'Wl'insecticides being made available to the public brings a challenge to theentomolog1st, which must be met by the most careful research methods.