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ORDER DIPTERA -- FLIES AND MOSQUITOES

a. Adults have one pair of wings (di = 2, ptera = wings).

b. Adults have sponging (house fly) or piercing (mosquito) mouthparts.

c. Larvae may have mouth hooks or chewing mouthparts.

d. Most larvae don't have legs, or a head capsule and commonly are called maggots.

e. Diptera have complex metamorphosis.

The flies encountered most frequently around households are the house fly, the green or blue bottle fly, and the stable fly. The grayish adults of the house fly infest homes, poultry houses and livestock. Fly larvae or "maggots" are generally found in manure, spilled feed, and other wet, decaying organic matter. Gnats may live and breed in the soil of houseplants within homes. They do no damage to the plants, but may become nuisances.

Commercial agricultural insect pests in this order include the fruit fly, leafminer fly, onion maggot, carrot rust fly and seed corn maggot.

Some species live in water as larvae and may become a nuisance around recreational ponds and lakes. For example, chironomid midges are feathery flies about 1/4 inch long that may emerge in clouds and annoy homeowners and boaters around waterways. The adults do not bite, but may cause allergic reactions. The larvae of mosquitoes also live in water. The adults are slender, long-legged, frail flies. The adult female is able to suck blood from a number of different animals, including humans, and some species can transmit diseases such as equine encephalitis and malaria.

Other medically important species, such as bot flies, are parasites of animals as immatures. The activity of some flies, such as the horn fly, disrupt or annoy livestock to the extent that the animal stops feeding, causing economic losses for farmers.

On the other hand, flies may be beneficial because they may be parasites of insect pests. For example, there is a tachinid fly that lays its eggs in gypsy moth larvae. The fly larvae feed within their host until they reach maturity, and pupate. The host is eventually killed. Many flies are excellent pollinators of flowering plants, including hover, flower, bee and tachinid flies.

ORDER HYMENOPTERA -- ANTS AND WASPS

a. Adults have two pairs of membranous wings.

b. The larvae lack legs, except for the sawfly larvae which resemble caterpillars. Sawfly larvae have legs on both their thorax and abdomen.

c. Most have chewing mouthparts both as adults and as larvae.

d. Many adult females have the ability to sting.

e. Members of the order Hymenoptera have complex metamorphosis.

This group also contains a large number of species. Many are important pollinators of agricultural crops, such as the honey bee, leafcutter bee, and alkali bee. Some are important predators or parasites and scavengers; some of the others may be injurious to crops. The social species, such as honey bees and ants, are highly developed, and exhibit many complex behaviors.

An example of a sawfly is the pearslug, which is a pest of pear, cherry and plum. The immature is slug-like, hence the name. It feeds on leaves. The adults are black with yellow markings. The immatures of other sawflies closely resemble caterpillars, for example the European pine sawfly. Larvae feed in groups on pine needles. The adults are wasp-like, except they have heavy bodies that are not constricted at the waist.

Some common wasps include yellow jackets. The adults build nests in the ground, or papery structures on trees, under eaves, etc. Stings are painful, and may be dangerous to a person who is allergic to them. However, these wasps also feed on a number of different caterpillars, and other insects, and in that manner are beneficial predators.

Leafcutting bee adults are about 1/2 to 3/4 inch long and variable in color. They are noted for their long tongues, which allow them to pollinate crops such as alfalfa. The leafcutter bee gets it name from the fact that it cuts neat circles from the leaves of shrubs and trees. It uses these pieces of leaf to create a snug chamber for its larvae.

Ants also belong to the order Hymenoptera. Some common ants found in houses include carpenter ants, the pavement ant, the odorous house ant, and the southern fire ant. Ants tend to feed on other insects, and thus are beneficial predators.