Wasp is any of a large number of insects closely related to bees and ants. There are more than 17,000 species of true wasps. They are characterized by a narrowing of the abdomen into a thin “wasp waist,” and by the presence of a sting in the female.
Wasps are most common in regions with tropical or warm climates. Only a few species live in cold regions. About 3,800 species are found in the United States and Canada. Most wasps have wings and fly. However, the females of a few species, called velvet ants, lack wings. The majority of wasps are yellow, reddish, bluish-black, or black in color. Some are black and white, black and yellow, or black and red. Others have stripes of black and a bright color across the body.
Scientists divide wasps into two groups: (1) solitary and (2) social. Each group has different nesting habits. Among solitary wasps, the female does all the work of nesting by herself. Common solitary wasps include mud daubers, cuckoo wasps, and digger wasps. Social wasps have a social system in which members of the community help build and maintain the nest. Hornets and yellow jackets are two common kinds of social wasps. 
Body.
A wasp’s body, like that of any insect, has three parts: (1) a head, (2) a thorax, and (3) an abdomen. On each side of its head, a wasp has two compound eyes made up of many tiny lenses. Two antennae between the eyes serve primarily as organs of smell and touch. A wasp’s mouthparts are designed both for chewing food and for sucking up liquids.
The thorax is the middle part of a wasp’s body. The insect’s wings and legs are connected to the thorax. Wasps have four wings and six legs.
A wasp’s abdomen contains organs of digestion and reproduction. Female wasps have a sting hidden near the end of the abdomen. Solitary wasps use their sting to paralyze prey. Social wasps also use their sting to defend their nest against intruders. Attached to a wasp’s sting are glands that produce poison. The poison of social wasps contains chemical compounds that are irritating to higher animals. People who are especially sensitive to these poisonous compounds can die from being stung.
Life cycle.
Wasps develop in four stages: (1) egg, (2) larva, (3) pupa, and (4) adult. The egg of a wasp hatches into a wormlike larva, also called a grub. The larva reaches its full size in 7 to 20 days, depending on the species and the weather. It then spins a covering known as a cocoon. Most solitary wasps that live in cool climates spend the winter in the cocoon. Most social wasps stay in the cocoon about two weeks. While in the cocoon, the larva becomes a pupa, a stage during which the insect changes dramatically into an adult. At the end of the pupal stage, the adult breaks out of the cocoon. 
Social wasps most commonly mate in the fall. The female hibernates during winter in a protected place and emerges in the spring to start a nest. Female solitary wasps hibernate as larvae and mate in the spring, after they have become adults. Both female social wasps and female solitary wasps store sperm (male sex cells) in a sac near the end of the abdomen. When a female wasp lays an egg, she may fertilize it with sperm. Fertilized eggs become female wasps, while unfertilized eggs become males. Mated female social wasps may live up to a year. All other types of wasps usually live two months or less.
Food.
Adult wasps feed mainly on the nectar of flowers. They prey on other insects and on spiders chiefly to provide food for developing offspring. Most species of wasps hunt a particular kind of prey. For example, one species of sphecid wasp preys on cockroaches. Another wasp species, the bee wolf, preys on honey bees.
In most species of solitary wasps, the female captures and paralyzes a prey by stinging it. She then puts it in a nest and lays an egg on the animal’s body. The larva that hatches from the egg feeds on the prey. A few solitary wasps and most social wasps capture a prey and immediately eat it. Later, they regurgitate (spit up) the food to their larvae.
Nests.
Wasps are talented nest-builders. Most solitary wasps dig nesting burrows in the ground. Some of these wasps nest above the ground in hollow twigs or abandoned beetle burrows. They separate the chambers for each offspring with bits of grass, stone, or mud. Other solitary wasps build nests completely of mud.
Most social wasps make their nests of paper. The female produces the paper by chewing up plant fibers or old wood. She spreads the paper in thin layers to make cells in which she lays her eggs. Some species of wasps, including a group called Polistes, build open nests with a single comb of cells. Other species, such as hornets and yellow jackets, construct nests of many cells enclosed by a paper covering with a single entrance. The nests may be suspended from trees, or they may be built underground in abandoned rodent burrows. A few kinds of social wasps build delicate mud nests.
Group life.
Solitary wasps do not live in groups. In most species, the male and female get together only to mate. The female maintains the nest and provides food for her offspring. Soon after emerging from the cocoon, each of the offspring leaves the nest and seeks a mate.
Social wasps live in organized communities that consist largely of members of the same family. In the spring, the mated female, called the queen, builds the first cells of the nest and lays eggs. Her first offspring are small females, most of which remain unmated and cannot reproduce. These females, called workers, enlarge the nest, care for new larvae, and defend the nest from intruders. The queen continues to lay eggs until late summer. Her last offspring include both males and larger females that can reproduce. Among some species, the queen may be joined by other queens, usually her sisters. If the founding queen dies, one of the other queens will take over her position.
Some social wasps that live in tropical climates establish new communities by swarming. Swarming occurs when a nest becomes overcrowded. One or more of the young queens leave the nest with several workers. Huddled together, the wasps fly to another location and build a new nest.
