Review Sheet -- Test 2 (Week 6) Biology 1224 -- Entomology; James Adams
Infraclass Neoptera; Division Exopterygota (continued)
Superorder Hemipteroidea --
Hemipteroid Orders (Chapter 15, page 316-317; Table 15.2;
Characteristics: primitive types have chewing mouthparts, most (more advanced) types have
sucking mouthparts; typically shorter antennae (than orthopteroids); cerci typically absent;
forewings dominate in flight; central nervous system concentrated in thorax; 4 or 6 Malpighian
tubules in the excretory system; nymphs with no ocelli.
As stated under the Orthopteroidea, the placement of the Zoraptera is tentative in the
Hemipteroidea, as they share some characteristics with the orthopteroids (chewing mouthparts;
cerci). Nymphs found in same habitats and utilize similar foods as the adults. Hemimetabolous,
except in the Thysanoptera which are functionally holometabolous*. The fossil groups of these
insects from the Paleozoic suggest these insects were more abundant and diverse in the past.
Order Zoraptera --
the zorapterans (Chapter 31)
Very small; prognathous with mandibulate mouthparts; prothorax typically large, often
larger than meso- or metathorax; several species wingless; wings membranous with reduced
venation in alate species; forewings larger than hindwings (typical of hemipteroids); legs adapted
for walking, with two segmented tarsi; tiny cerci. Asymmetrical male genitalia, in some ways like
the roaches and termites, wing musculature also similar to roaches; however, nervous system is
concentrated in the thorax and anterior abdomen, the larger forewings have reduced
venation, more like hemipteroids. Resemble termites a bit and often inhabit dead wood,
moist leaf litter, etc. apparently feeding on fungi and occasional small arthropods. Some species
have different adult forms, wingless and alate, with the alate forms probably for dispersal;
development of the winged forms may be in response to unfavorable environmental conditions. In
at least one species, males do a courtship dance; while mating, female drags male around on back.
About 30 known species, all in the family Zorotypidae. One species (Zorotypus hubbardi)
occurs here in the SE U.S.
Order Psocoptera --
the psocids; book lice and barklice (Chapter 32)
Small; head proportionally large and mobile, with large eyes and swollen clypeus; chewing
mandibles; the maxillae have a rod-like projection that steadies the head during feeding; winged
and wingless species; prothorax quite small; meso- and metathorax a bit larger, particularly in
winged forms; wings membranous with simple venation; forewings typically one and a half times as
long as hindwings; walking legs with 2-3 tarsal segments; no cerci.
Typically scavengers on organic materials, such as paper, dead insects, plant specimens,
etc. Can cause significant damage in collections if unchecked. Other species feed on plant
surfaces (barklice). Rod-like projections off of the maxillae steady head while scraping with the
mandibles on lichen, algae, fungi, etc. Many species solitary, though large groups may occur
where food is plentiful. Other species are gregarious, and some species can spin silk from glands
in the labia; may have large colonies in trees. As with zorapterans, some species have both
wingless and winged adults. Courtship dances lead to mating, with male and female positioned
end-to-end. Some species have live birth. Many species are parthenogenetic, with females
producing more females except under stressful circumstances (males extremely rare and even
unknown for some species).
About 3000 species worldwide, and sometimes incredibly abundant.
28 families (!) occur north of Mexico, but most common are the Psocidae.
Order Phthiraptera --
Lice (Chapter 33)
Small ectoparasites on vertebrates (birds or mammals, including man); body streamlined or
flattened; head with eyes reduced or absent; antennae typically very short; wingless; mouthparts
mandibulate or highly modified for piercing/sucking materials from host; mobile legs short and
stout with modified claws for grasping hairs/feathers on host; no cerci.
Most species are scavengers on organic debris (dried skin, etc.); a few will pierce skin and
suck blood or feed on other secretion (oils from the skin). Even mandibulate species feeding on
surface cells, however, can cause tiny lacerations and irritation, which can be severe with heavy
infestation. All species stay with host through all stages, and will not survive long if off the host.
The vast majority of species are host specific, sometimes to particular parts of the body. Species
on marine animals may hop off hosts in resting sites on land while hosts are at sea.
Mating occurs on host (a few are parthenogenetic); eggs laid a few at a time (WHY?).
Amblycera and Ischnocera -- the biting lice (mandibulate); often classified as Mallophaga
Similar in appearance to psocids, with similar mouthparts, including maxillary rods.
Anoplura -- the sucking lice
Mouthparts with stabbing stylets, withdrawn into a pouch in the head capsule when not in use.
Small teeth around the mouth opening anchor the head while the stylets puncture the skin. The
main family specializing on primates (that= d be you!) is the Pediculidae, and includes the body
louse (Pediculus humanus) and the pubic or crab louse (Phthirus pubis).
3000+ species worldwide; with anywhere from 1 to 6 species (rarely up to 15) per host,
and sometimes individuals may number in the thousands on a host.
Order Thysanoptera --
the thrips (Chapter 35); by the way, it is "one thrips"
Quite small; slender elongate body; head hypognathous or opisthognathous; mouthparts
asymmetrical, with maxillae and left mandible piercing; large eyes; antennae moderately short;
thorax segments approximately equal in size; meso- and metathorax fused; wings narrow, with
proportionally huge setal fringe; some species wingless; legs adapted for walking, with 1 to 2
tarsal segments, with a special glandular vesicle. Functionally *holometabolous, with pupal stage;
though still exopterygous; some species spin a cocoon
Very widespread order, with species inhabiting a broad spectrum of vegetation and plant
debris, including flowers. Of economic importance, as the modified piercing mouthparts are
usually for getting at plant juices, particularly in buds, flowers and young fruits; many transmit
plant diseases. Some species are predators of small insects, such as aphids or eggs of mites and
Lepidoptera. Some species may bite humans defensively. The reduced wings are seen in other
very small insects. Even so, thrips are competent fliers; may be blown long distances in the wind.
The special tarsal vesicle is adhesive, for clinging to smooth surfaces (petals). Female thrips
diploid, males haploid (come from unfertilized eggs). Adults may exhibit wing polymorphism, as
in Zoraptera and Psocoptera. Typically occur in large congregations on foodplants
Suborders: Tubulifera -- end of abdomen with tubular projection (unspecialized ovipositor)
One family (Phlaeothripidae)
Terebrantia -- females with serrate (cutting) ovipositor.
Most common family is the Thripidae.
About 4500 species worldwide, with significant diversity in temperate and subtropical regions.
Order Hemiptera --
(Chapter 34); you will need to KNOW the families indicated
with a "*"
Tiny to quite large insects; piercing and sucking mouthparts. Strongly sclerotized head
with typically large eyes; mandibles/maxillae extremely long and needlelike, sheathed in a long
tubular labium; no palps. Prothorax typically large; mesothorax often with enlarged
triangular scutellum; metathorax smaller. Forewings larger than hindwings (typical for the
superorder); wings flexed backwards over the abdomen. Legs typically walking, but hopping
forms with enlarged hindlegs, and predatory forms may have raptorial forelegs; three or fewer
tarsal segments. First abdominal segments often reduced; last abdominal segments often fused;
no cerci. Many species can produce sound, from different structures in the two suborders (see
below); sound production is typically for attracting mates. For most terrestrial forms, mated
individuals are typically mating end to end; some Homopteran families have a number of species
that are parthenogenetic (many aphids, for instance). Eggs are laid singly or in groups, and for
those that do lay eggs in groups, there is some egg guarding by females. Nymphs similar to
adults, though nymphs may go through striking color changes as they molt, and adult pattern may
bear little resemblance to that of the nymphs. In a few families, major morphological changes
(besides color) may occur from between nymphal instars and into the adult; some functionally
holometabolous. Nymphs in several families produce "honeydew" and are tended by ants; others
cover themselves with secretions for protection; still others grow inside plants and produce galls.
Most are feeders on plant juices, using their piercing and sucking mouthparts to get to the
juices. Plant juices are not nutritionally complete, and so most species have bacterial or fungal
(yeast) symbiotes in their guts that provide them with extra nutrients; these symbiotes are actually
passed through eggs to the next generation. When they pierce tissues, they typically also release
"saliva" which may have extra digesting enzymes which will further break down food tissues, as
well as introducing microorganisms, particularly plant viruses. Additionally, predatory species have
toxic, paralyzing compounds in their saliva; many may painfully bite humans.
The endopterygotes have no orders that have successfully invaded this "sucking plant juices"
niche to any great extent, probably because the Heteroptera have kept them excluded.
55,000 plus species make this the fifth largest order in the world; species in this order are
found on all continents except Antarctica.
The two suborders of this large order (Heteroptera and Homoptera) are often treated as
separate orders, with the Heteroptera retaining the name Hemiptera. More recent treatments of
this order, however, split the suborder Homoptera into two other suborders: Auchenorrhyncha
and Sternorryncha (as indicated below).
Heteroptera ("different wings") -- the True Bugs: Forewings typically half leathery
(basally) and called the corium, half membranous (terminally). Most species are plant feeders,
but a few are predatory (or parasitic), some of which are abundant enough to have an effect on
other insects populations. All aquatic families are predaceous, and some families (like Gerridae)
are successful in marine habitats. Many species in this group also secrete smelly compounds for
protection (eg., stink bugs), and are often quite brightly colored to indicate distastefulness. Sound
production is by means of various stridulatory structures in different families.
Likely encountered families in the Heteroptera include:
Cydnidae: Burrowing bugs -- dark in color; resemble round beetles
*Pentatomidae: Stink Bugs &
Shield-Backed Bugs (separated as Scutellaridae by some)
*Coreidae: Leaf-Legged Bugs (including the Squash Bug)
*Lygaeidae: Seed bugs (though a few species predatory)
*Rhopalidae: Scentless Plant Bugs; includes the very common Box Elder Bug
Berytidae: Stilt bugs
Tingidae: Lace bugs; some species= nymphs tended by ants
*Reduviidae: Assassin bugs; elongate body form and most predatory
(the subfamily Phymatinae [Ambush bugs] are treated as a separate family by some)
*Miridae: Leaf or Plant bugs
Nabidae: Damsel bugs; predaceous like reduviids
Cimicidae: Bed bugs
*Gerridae and Veliidae: Water Striders and Ripple Bugs
Corixidae: Water boatmen
Nepidae: Water scorpions
*Belastomatidae: Giant water bugs; some of the largest Heteroptera; bad bite!
Gelastocoridae: Toad bugs
Homoptera ("same wings"): Forewings typically all leathery or all membranous. Members
of this suborder are almost exclusively plant feeders, stabbing their mouthparts into the
stems/roots to feed on the nutrient-rich fluids coursing through the plants. Sound production,
which can be particularly loud in cicadas, is produced by vibrations of tymbals at the base of the
abdomen. Nymphs of some families (Aleyrodidae, Coccoidae) may and be completely non-motile
and cover themselves in some instars with hard secretions that protect them from predators.
Likely encountered families in the Homoptera include:
*Cicadidae: Cicadas; some species spend long periods as nymphs underground
*Fulgoridae, Flatidae, Cixiidae, Acanaloniidae, Derbidae (and others): Planthoppers
*Cercopidae: Froghoppers and spittlebugs
*Membracidae: Treehoppers (A thorn@ bugs); nymphs often tended by ants
Aleyrodidae: Whiteflies; minute pests on leaves, most important on citrus trees
*Aphididae: Aphids; gregarious, some tended by ants, some defend colonies;
economically quite important because in numbers can damage plants
Coccidae (and related familes): Scale insects and mealybugs