Bald-faced hornets build football-sized and -shaped paper nests in trees and shrubs. The one-inch-long black hornets with whitish faces and rear ends fly in and out of an opening near the bottom of the nest. In the evening, soak the nest through this opening with diazinon or wasp and hornet spray. This species of wasp posts guards outside the nest day and night, so be sure to wear protective clothing.

Honeybees are amber or brown and black banded, hairy, and about 1/2 inch long. They nest in the hollows inside tree trunks and build walls in colonies that may contain tens of thousands of individuals. They also swarm in groups of several hundred, particularly in the spring. The swarm is likely to form a mass of bees on a tree branch or other support. Most of these swarms leave on their own within a few days. Ones that remain after a week may need to removed by a beekeeper or sprayed with an insecticide. Honeybees in swarms are usually docile and those with colonies in trees rarely attack unless provoked. The Africanized honeybee or so-called "killer bee" looks like any other honeybee but attacks from the hive more readily and swarms more easily. The only place where it is found in North America is Mexico and the southwestern United States.

Yellowjackets are 1/2-inch-long, black-and-yellow-banded wasps that many people call "bees." They live in underground nests in old rodent burrows. They may also make a nest in a woodpile, pile of brush, hollow tree, or wall of a house. Late in the summer, nests may contain several thousand wasps. Of the Illinois bees and wasps, this is probably the most likely to sting.

Bumblebees are 1/2- to one-inch-long, yellow and black, hairy, stout-bodied insects that nest underground. There are usually fewer than 60 individuals per nest, which is usually built in an old rodent burrow.

Burrowing bees are hairy, 1/2-inch-long bees that are usually drab in color, with bands of black and brown or gray. They make individual nests in the ground with 1/4-inch openings. Often, many individuals nest in the same area; the bees tend to fly about six inches above the nest. They are very unlikely to sting. Weeding, trimming, and even tilling can usually be done in the nest area without the risk of being stung.

Cicada killers are about 1-1/2 inches long, have reddish transparent wings, and are black with yellow bands. Sand wasps may be reddish or grayish and up to two inches long. Cicada killers and sand wasps build individual nests with 1/4- to 1/2-inch entry holes in the soil. Males usually patrol the air space above the nests and will zoom around passersby, creating a considerable amount of anxiety. Because these wasps rarely sting people (although they will sting if stepped on or grabbed), control is not necessary unless residents can't control their fear or the wasps are being a problem to golfers.

Tiphiid wasps are slender, one-inch, yellow-and-black-banded wasps. Scoliid wasps, also about one inch long, are stouter wasps that are black with an abdomen that is predominantly orangish. Both wasps feed as larvae on white grubs and thus are beneficial. These wasps may be numerous in turf areas, particularly in southern Illinois. They are unlikely to sting.

Leafcutter bees are about 1/4-inch, gray-and-black-banded, and hairy. Small carpenter bees are also about 1/4-inch long and hairy, but are roundish with yellow and black bands. Both nest in the stems of flowers, weeds, and shrubs, hollowing out the pith to make a suitable cavity. They commonly nest in the pruned ends of rose, raspberry, and blackberry. Leafcutter bees separate and surround the larval cells in the stems with 1/2-inch diameter, circular pieces of leaf tissue that they cut out of rose, redbud, maple, and other leaves. Neither bee is likely to sting.