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
•
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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 neoDarwinian 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 overwinters 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 yardlight 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 dungflies (may have arisen
during pre-dinosaur
mammalian radiation).
• Vectors of several
important diseases
(e.g., plague).