Some Common Insect “Orders”

1. Some Common Insect “Orders”

2. 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.

3. 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….

4. 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.

5. 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.

6. 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.

7. 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….

8. 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!

9. 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!

10. 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.

11. 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….

12. 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...

13. 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.

14. 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.

15. 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.

16. 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.”

17. 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….

18. 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, …

19. 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…).

20. 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).

21. 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.

22. 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.

23. 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….

24. 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!

25. 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).