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).