Wasps

The term wasp is typically defined as any insect of the order Hymenoptera and suborder Apocrita that is neither a bee nor an ant. Almost every pest insect species has at least one wasp species that preys upon it or parasites it, making wasps critically important in natural control of their numbers, or natural bio control.

Parasitic wasps are increasingly used in agricultural pest control as they prey mostly on pest insects and have little impact on crops. 

The majority of wasp species (well over 100,000 species) are “parasitic” (technically known as parasitoids), and the ovipositor is used simply to lay eggs, often directly into the body of the host.

The most familiar wasps belong to Aculeata, a division of Apocrita, whose ovipositors are adapted into a venomous sting, though a great many aculeate species do not sting. Aculeata also contains ants and bees, and many wasps are commonly mistaken for bees, and vice-versa. In a similar respect, insects called “velvet ants” (the family Mutillidae) are technically wasps. 

The various species of wasps fall into one of two main categories: solitary wasps and social wasps. Adult solitary wasps live and operate alone, and most do not construct nests (below); all adult solitary wasps are fertile. By contrast, social wasps exist in colonies numbering up to several thousand individuals and build nests—but in some cases not all of the colony can reproduce. In some species, just the wasp queen and male wasps can mate, whilst the majority of the colony is made up of sterile female workers. 



Anatomically, there is a great deal of variation between different types of wasp. Like all insects, wasps have a hard exoskeleton covering their three main body parts. These parts are known as the head, mesosoma and metasoma. Wasps also have a constricted region joining the first and second segments of the abdomen (the first segment is part of the mesosoma, the second is part of the metasoma) known as the petiole. Like all insects, wasps have three sets of two legs. In addition to their compound eyes, wasps also have several simple eyes known as ocelli. These are typically arranged in a triangular formation just forward of an area of the head known as the vertex. It is possible to distinguish between sexes of some wasp species based on the number of divisions on their antennae. Male yellowjacket wasps, for example, have 13 divisions per antenna, while females have 12. Males can in some cases be differentiated from females by virtue of having an additional visible segment in the metasoma. The difference between sterile female worker wasps and queens also varies between species but generally the queen is noticeably larger than both males and other females. Wasps can be differentiated from bees, which have a flattened hind basitarsus.

Unlike bees, wasps generally lack hairs. Generally wasps are parasites or parasitoids as larvae, and feed only on nectar as adults. Many wasps are predatory, using other insects (often paralyzed) as food for their larvae. A few social wasps are omnivorous, feeding on a variety of fallen fruit, nectar, and carrion. Some of these social wasps, such as yellow jackets, may scavenge for dead insects to provide for their young. In many social species the larvae provide sweet secretions that are fed to the adults. In parasitic species, the first meals are almost always provided by the animal that the adult wasp used as a host for its young. Adult male wasps sometimes visit flowers to obtain nectar to feed on in much the same manner as honey bees. Occasionally, some species, such as yellow jackets and, especially, hornets, invade honey bee nests and steal honey and/or brood. The type of nest produced by wasps can depend on the species and location.

Many social wasps produce nests that are constructed predominantly from paper pulp. The kind of timber used varies from one species to another and this is what can give many species a nest of distinctive color. Social Wasps also use other types of nesting material that become mixed in with the nest and it is common to find nests located near to plastic pool or trampoline covers incorporating distinct bands of color that reflect the inclusion of these materials that have simply been chewed up and mixed with wood fibers to give a unique look to the nest. Again each species of social wasp appears to favor its own specific range of nesting sites.