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).