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Lecture 7: The Insect Orders II: Isoptera >>> HomopteraLecture 7 spans the following orders:
To cover this range of orders, lecture 7 devotes only a little time to each. In addition, the Embioptera and Zoraptera are not discussed at all in this course. Isoptera: The termites
Iso = equal; ptera = wing; fore and hind wings are nearly identical Web sites to check ... Description and identification: Adult:
Immature: Like adult Similar orders: Hymenoptera (narrow "waist" between thorax and abdomen) and Psocoptera (2- or 3-segmented tarsi; longer antennae) Habitat: Nests (colonies) in wood or soil; feed directly on wood, wood products, and similar high-cellulose materials. Pest or Beneficial Status: Severe pests of wood and related products; key in breakdown of plant debris. Eastern subterranean termite is most troublesome in the eastern United States. This species nests in the ground and workers must be protected from dry air by the tunnels or mud tubes. Drywood and dampwood termites also are present in the U.S. Abundance in North America: 4 families, 42 species Dermaptera: The earwigs
Derma = skin; ptera = wing ... refers to the skin-like texture of the front wings Web sites to check: Description and identification: Adult:
Immature: Like adult, but wingless. Add antennal segments with each molt. Similar orders: Coleoptera: rove beetles resemble earwigs but lack pincer-like cerci. Habitat: Moist debris and decaying materials. Nocturnal ... feed on plants or decaying plant material; some are predaceous. Pest or Beneficial Status: Earwigs are usually pests only as nuisance creatures, but one species, the European earwig, Forficula auricularia L. (Dermaptera: Forficulidae), is a pest of vegetables, ornamental plants, and fruits. Its feeding leaves scars on the surface of apples and pears (not a key pest). Abundance in North America: 6 families, 22 species Plecoptera: The stoneflies Pleco = folded; ptera = wing ... refers to the fact that the anal portion of the hind wing is folded when the wings are at rest. Description and identification: Adult:
Immature:
Metamorphosis: Incomplete Similar orders:
Habitat: Immatures are aquatic; adults near water. Naiads feed on plants or are predators; adults feed on plants. Pest or Beneficial Status: None (except fish food) Abundance in North America: 9 families and approximately 540 species Psocoptera: The psocids (booklice and barklice)
Psoco = rub small; ptera = wings; refers to the gnawing habits of these insects Web sites to check: Description and identification: Adult:
Immature: Like adult Habitat: Debris, under bark, sometimes in buildings; feed on dry organic matter, molds, algae, lichens, cereal products Pest or Beneficial Status: Nuisance; some contaminate stored grains and cereal products; may eat starchy glues used in book bindings; usually associated with damp conditions and molds Abundance in North America: 13 families, 280 species (An authority on the Psocoptera is Dr. Ed Mockford at Illinois State University in Normal.) Phthiraptera: The lice Phthir = lice; aptera = without wings The Phthipraptera is divided into two suborders, considered by some to be separate orders ... The Chewing lice:
Description and identification:
Immature: Like adult Similar groups: The suborder Anoplura (sucking mouthparts, head narrower than thorax) Habitat: Ectoparasites of birds and mammals Pest or Beneficial Status: Some species are important pests of poultry and livestock. Abundance in North America: 7 families; 320 species The Sucking Lice Description and identification: Adult:
Immature: Like adult Similar orders: Mallophaga (wide head; chewing mouthparts; some with 2-segmented tarsi) Habitat: Ectoparasites of mammals Abundance in North America: 9 families; 70 species Hemiptera: Suborders are Heteroptera, the true bugs, and Homoptera, the cicadas, hoppers, psyllids, whiteflies, aphids, and scales. Hetero = different; ptera = wing; refers to the half-sclerotized, half membranous forewing
Web sites to check: Description and identification: Adult:
Immatures: Like adults Similar orders: Coleoptera (front wings are modified as full elytra without veins; Homoptera: forewing completely membranous; beak arises from the base of the head. Habitat: Some groups are aquatic; most feed on plants; several families are predaceous on other insects; a few species are ectoparasites of animals. Pest or Beneficial Status: Several important crop pests (including Lygus bugs, stink bugs, chinch bug, squash bug); several beneficial predators (damsel bugs; big-eyed bugs, minute pirate bugs), and a few pests of humans (bed bugs and Triatoma, the vector of Chagas disease). Abundance in North America: 44 families, 4,600 species Selected Groups of Hemiptera: Miridae: The plant bugs and leaf bugs: Recognize mirids by their having a cuneus on the hemelytra (a cell set off by a crease) and 2 closed cells in the membrane of the forewing.
One genus that contains important pests of many plants is Lygus. Lygus bugs are serious pests in cotton, alfalfa seed, and fruit production. Lygaeidae: The seed bugs: The Lygaeidae contains many plant-feeding species, among them the chinch bug, a serious pest of corn and wheat in the Southern Plains and an occasional pest of turf as well. Coreidae: The leaf-footed bugs: Several species of the coreids have the hind tibia flattened to resemble a leaf; all have scent glands on the thorax between the mid and hind coxae. A key pest in this group is the squash bug, Anasa tristis. (Its hind tibiae are NOT flattened or leaflike.) Pentatomidae: The stink bugs: The Pentatomidae contains several important pests of crops, including the green stink bug, the brown stink bug, and the harlequin bug In addition to the pest species of the Pentatominae, the subfamily Asopinae contains several predaceous species, notably the spined soldier bug. Unlike the brown stink bug, it has a forward-projecting spine between the hind coxae, a heavy basal segment in the beak, and darkened lines at the tips of the membranous portion of the forewing. Although the spined soldier bug is sold for use in biological control, its feeding rate and reproductive rate limit its value in "augmentation" efforts. Nabidae: The damsel bugs; Anthocoridae: the minute pirate bugs: The nabids (damsel bugs) and the minute pirate bugs are generalist predators of soft-bodied insects. Where their prey is NOT comprised of specialist predators, they can be important in the natural control of plant pests.
Homoptera: The cicadas, hoppers, psyllids, whiteflies, aphids, and scales
Homo = same; ptera = wing ... refers to the fact that the forewing is of a single quality ... completely membranous Web sites to check: Description and identification: Adult:
Immature: Like adult, but wingless Similar orders: Coleoptera (chewing mouthparts and elytra); Hemiptera (beak arises from tip of head; forewings are hemelytra) Habitat: On plants (foliage, stems, or roots); all species are plant-feeders Pest or Beneficial Status: Many important pests Abundance in North America: 38 families, 33,000 species Selected Groups of Homoptera: Aleyrodidae: The whiteflies
After the first instar, nymphs are inactive and scale-like; wings develop internally. A "pseudopupa" stage precedes adult emergence. Adults are covered with a white dust or waxy powder. Examples include the greenhouse whitefly and the poinsettia/sweet potato/silverleaf whitefly. (See the USDA’s Whitefly Knowledge Base.) Aphididae: The aphids Pear-like shape, posterior cornicles, and long antennae. Life cycles are often complex, with winged and wingless forms and winter and summer hosts. Parthenogenesis is common. Cicadellidae: The leafhoppers
Some leafhoppers "just" remove sap and chlorophyll (white apple leafhopper); others inject toxins or saliva that block xylem or phloem channels (potato leafhopper); others damage stems by egg-laying; still others carry pathogens (beet leafhopper; aster leafhopper). Cicadidae: The cicadas Annual or "dog-day" cicadas' life cycles take several years, but broods overlap, and some adults emerge every year. Periodical cicadas are synchronized in given regions. Damage to twigs of woody plants is caused by egg-laying females; nymphs drop to the ground and feed on tree roots. Superfamily Coccoidea -- The scales
Includes armored scales, soft scales and mealybugs. Newly hatched scales are mobile "crawlers" that soon insert their mouthparts into a plant, become sedentary, and secrete a waxy, cottony, or hardened covering. See the index of the text for examples of many pest species. See also: San Jose scale crawler Other Homopterans to check out (via the text and links): |
Introduction to Applied Entomology If you find any problems with this page, please notify Rick Weinzierl, weinzier@uiuc.edu. |
