Some Common

Insect “Orders”

Silverfish and their allies.

• 47 North American (NA) species, 580 species worldwide (WW).

• Primitive, wingless.• Body regions are not easily

distinguished.• Antennae & repro appendages

almost as long as head-body.• Do not undergo complete

metamorphosis.• Cuticle is not well developed, so

silverfish must inhabit high humidity environment.

Silverfish and Allies

• Largely nocturnal

• Related “firebats” are of tropical origins.

• This is the only widely known Order of truly primitive insects.

• Primitive (& interesting) fertilization requiring high-humidity….

Mayflies & allies.• 51NA, 580WW• These are the most primitive

widely known winged insects.• Larvae (left):

– are long-lived aquatic detritavores

– breathe through cuticle & gills

– have shape & habits for particular habitat

– remain larvae for 7-36 months.

• Adults (next slide) live just long enough to reproduce.

Mayflies, etc.

• Mass emergences occur in warm weather, usually in early evening.

• After larval stage:– Flying sub-adults (subimagoes)

– Flying adults (imagoes)

• Full adults typically move toward maximum light and mate in swarms.

• Eggs (or, in a few species, newborn larvae) are always placed into water.

Dragonflies & damselflies

• 450NA, 4950WW.• Primitive flying insects.• Adults long-lived fliers;

larvae long-lived aquatic predators

• Feeding strategies– Adults are aerial

insectivores (may have > 28,000 “eyelets”; may fly at 40-50kph).

– Juveniles are stalking or sit-&-wait predators that often dominate ephemeral aquatic habitats.

Dragonflies & Damselflies

• A wonderful web site (lists 148 South Carolina species w/pictures of 38) at www.npwrc.usgs.gov/resource/distr/insects/dfly/dflyusa/htm

• Mating is awkward (at least to describe); from 9th abdominal male loads sperm into second abdominal….

Grasshoppers, crickets, etc.• 1018NA, 12500WW• 3rd leg pair often modified

for jumping• Orthopterans show many

variations on that theme...• Communication

– Crickets rub outer wings– Grasshoppers rub jumping

legs against outer wings– Females locate by tuning to

the “null”…

• Many agricultural pests!

Migratory locusts: awesome grasshopper pests

• Populations often live in sedentary state, but under density stress they may change color, metabolism, and behavior– and move out!

• Swarms can be enormous:– Morocco, 1955:

20kmX250km

– Algeria, 1890: more than two trillion killed

• Eat every green plant-part!

Walkingsticks

• 27NA, 2000 WW.• Variable body form.• Arboreal folivores.• Most rely on

camouflage & stillness to avoid predators (though some have chemical defenses).

• Regenerate lost limbs.• Repro & gender ratios.• Sexual dimorphism.

Cockroaches

• 3000-4000 WW• Roaches are very

ancient (400mybp):– Scavengers– Perhaps earliest

cellulose processors

• Lay (or carry) egg cases of 2 to 30-40 eggs.

• Control of the beasts….

Mantids

• Mantids, top predators, have long, cylindrical bodies (1-17cm), triangular heads, and “preying” arms.

• Tropical species are more varied….

• Here are some neo-Darwinian meditations on mantid mating...

Termites.• 41NA, 1900 WW• Cellulose processors; symbiants….• Thin cuticles; high humidity.…• Nest constructions:

– Protection, water, humidity, thermoregulation

» Shelter for other animals….

• Africa’s Macrotermes can have > 2,000,000 individuals/mound.

• The primary herbivores of arthropod world; consider w/ants.

Termites: founding & living in colonies

• Swarming….• Production of nymphs• Colonial & eusocial:

– A colony includes reproductives (often, plus secondary reproductives), workers, and soldiers.

– Both genders of larvae are totipotent at hatching.

– Growing nymphs are locked into body-forms & immaturity by nutrition and hormones (contrast w/ ants, etc.).

– In most species, workers & soldiers have multiple forms.

True bugs• 4500NA, 23000WW.

• Great variety, but all have:– sucking mouth parts,– hard anterior wings partly covering

back wings.

• The Order includes herbivores and predators.

• The Order is agriculturally & medically significant.

• Some plant-eaters have generational differences correlated with plant developmental stages.

More on true bugs

• The Order includes bedbugs, stink bugs, water bugs, water striders, and much more....

• A few nasty notes on bedbugs:– Greatly flattened.– Multiple piercings in search of

surface capillary; delayed itching.– Slow to starve.– Reproduce by “traumatic

insemination.”

Cicadas (plus aphids, scale insects, leafhoppers, etc.)

• 6500NA, 32000WW• Bug-like (piercing) mouth

parts.• Eat exclusively plant juices

(…excess sugars, protein and nitrogen deficiencies, symbiants…).

• The cicada life cycle– 2, 14, & 17-year cycles in USA– Emerge (great swarms in some

species); short adult lives….

Beetles!!!!!

• 28600NA, 290000WW.• Range in size from 0.025mm to

150mm.• Hard forewings cover lacy hind-

(flight-) wings• The most successful animal Order!• Larvae are eating-machine grubs;

adults are highly varied, including predators, coprovores, sangrivores, herbivores, omnivores, …

Examples of beetle

lifeways:

• Ladybird beetles: hunters of scale insects & small caterpillars (eat about 3000).

• Lightening bugs: Only male goes through complete metamorphosis; females are glowworms.

• Some beetles are ant-colony invaders.

• Dung beetles (left) exploit large mammal feces.

• Micromalthus debilis over-winters as larvae; some pupate; others reproduce as larvae (small larvae or one big egg…).

Butterflies, moths, etc.

• 13700NA, 180000WW• Large scaly wings.• Extreme 2-stage life:

– Caterpillars eat & have simple body plan. Most are very food-specific. Many are agriculturally significant.

– Adults move and reproduce. Many have short lives, but consider the migratory monarch (left).

Butterflies, moths, etc.

• Long proboscis allows access to nectar.

• Most important adult taste organs on legs; this helps identify target flowers.

• Erratic flight patterns help avoid predators.

• Some large moths (upper left) navigate by moonlight & are endangered because of yard-light proliferation.

Wasps, bees, ants(hymenopterans)

• 17500MA, 103000WW• Some commonalities include:

– stinging, nest-building, colonial lifeways

– diploid females, haploid males

• Ancestral hymenopterans were like sawflies, gall wasps, etc. (top).

• Early descendents were parasitoid wasps (center).

• Solitary hunters (bottom) arose from parasitoids.

• Colonial wasps are more derived.

Hymenopterans (cont.)• Bees.

– Lifestyles almost as varied as wasps (solitary, colonial…).

– Honeybees: c. 40k & 1 queen per hive. Males from unfertilized eggs. Eggs rapidly into grubs; grow 6 days, pupate 12 days; nurse houseworker guard forager (@ 2-3 weeks). Queen designated by care.

• Ants are mostly predators….– Leafcutters, pastoral ants (honeypots)….

– Slaver ants….

– Driver ants (20 million workers, 65kg)…

• Founding a new colony. Nuptial flight; males die; small, timid 1st workers….

Flies, mosquitoes, etc.

• 16130NA, 85000WW

• Only 1 pair of wings. (Some “flies” are wingless & parasitic.)

• Larvae generally legless (aquatic in mosquitoes).

• This group has extreme medical importance!

Fleas• 238NA, 1370WW

• Small, hard-bodied, wingless; perhaps descended from dung-flies (may have arisen during pre-dinosaur mammalian radiation).

• Vectors of several important diseases (e.g., plague).