Review Sheet -- Test 2 (Week 6) Biology 1224 -- Entomology; James Adams
Infraclass Neoptera; Division Exopterygota (continued)
Superorder Hemipteroidea --
Hemipteroid Orders (Chapter 16, page 332; Figure 16.5;
Characteristics: primitive types have chewing mouthparts, most types have sucking mouthparts;
typically shorter antennae (than orthopteroids); cerci absent; forewings dominate in flight; central nervous
system concentrated in thorax; 4 or 6 Malpighian tubules in the excretory system; nymphs with no ocelli.
Hemimetabolous, though there are a few Thysanoptera and Hemiptera 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 Psocoptera -- the psocids; book lice and barklice (Chapter 32); recent molecular evidence
suggests that the following order (Phthiraptera) should actually be included within this order.
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, that may include paper and bindings of books, as
well as dead insects and plant specimens, so some are pests in libraries and biological collections.
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 wingless and winged
adults. Courtship dances present in some species, though quite variable in the three suborders.
Some species have live birth. Number of instars varies from three in certain apterous species up
to six in fully winged psocids. Many species are parthenogenetic, with females producing more
females except under stressful circumstances (males extremely rare or unknown for some species).
About 5000 species worldwide, and sometimes incredibly abundant.
3 suborders, and 28 families (!) occur north of Mexico, but most common are the Psocidae.
Order Phthiraptera --
Lice (Chapter 33)
As indicated above, this order will likely be "absorbed" into the Psocodea due to the close
relationship of members of this order with families in the Psocoptera
Small ectoparasites on vertebrates (all orders of birds; most orders of mammals [including primates
and 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?).
Suborders: (not responsible for Rhynchophthrina)
Amblycera (horizontally) and Ischnocera (vertically oriented mandibles) -- the biting lice.
Similar in appearance to psocids, with similar mouthparts, including maxillary rods; mostly on
Anoplura -- the sucking lice; 250 or so species restricted to placental mammals.
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 a special
glandular vesicle. Some 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, buds and fruits. Of economic importance, as the modified piercing
mouthparts are usually for getting at plant juices, particularly in buds, flowers and young fruits; a
few 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. Some cause gall formation,
and some are even important pollinators. 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 Psocop-
tera. Typically occur in large congregations on foodplants. Generations can be extremely fast in
some species, achieving adulthood from hatching within 10 days.
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 5000 species worldwide, with significant diversity in temperate and subtropical regions.
Order Hemiptera --
the "True Bugs@
(Chapter 34); 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
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 Hemiptera 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 three suborders of this large order that you will need to know are the Heteroptera,
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
Auchenorrhyncha and Sternorrhyncha: Forewings typically all leathery or all membranous.
Members of this suborder are 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 Auchenorrhyncha 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
Likely encountered families in the Sternorrhyncha include:
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