Wasp — A wasp is any insect of the order Hymenoptera and suborder Apocrita that is not a bee or ant. The suborder Symphyta includes the sawflies and wood wasps, which differ from members of Apocrita by having a broader connection between the mesosoma and metasoma. In addition to this, Symphyta larvae are mostly herbivorous and “caterpillar like”, whereas those of Apocrita are largely predatory or “parasitic” (technically known as parasitoid).
The most familiar wasps belong to Aculeata, a division of Apocrita, whose ovipositors are adapted into a venomous stinger. Aculeata also contains ants and bees. In this respect, insects called “velvet ants” (the family Mutillidae) are technically wasps.
A much narrower and simpler but popular definition of the term wasp is any member of the Aculeate family Vespidae, which includes (among others) the genera known in North America as yellow jackets (Vespula and Dolichovespula) and hornets (Vespa).
The various species of wasp fall into one of two main categories: solitary wasps and social wasps. Adult solitary wasps generally live and operate alone, and most do not construct nests; all adult solitary wasps are fertile. By contrast, social wasps exist in colonies numbering up to several thousand strong and build nests—but in some cases not all of the colony can reproduce. Generally, just the queen and male wasps can mate, whilst the majority of the colonies are made up of sterile female workers.
In wasps, as in other Hymenoptera, sexes are significantly genetically different. Females have a diploid (2n) number of chromosomes and come about from fertilized eggs. Males, in contrast, have a haploid (n) number of chromosomes and develop from an unfertilized egg. Wasps store sperm inside their body and control its release for each invididual egg as it is laid; if a female wishes to produce a male egg, she simply lays the egg without fertilizing it. Therefore, under most conditions in most species, wasps have complete voluntary control over the sex of their offspring.
Generally wasps are parasites as larvae, and feed only on nectar as adults. Some wasps are omnivorous but this is relatively uncommon, they feed on a variety of fallen fruit, nectar and carrion. Many wasps are predatory, preying on other insects. Certain social wasp species, such as yellowjackets, scavenge for dead insects to provide for their young. In turn the brood provides sweet secretions for the adults.
In parasitic species the first meals are almost always provided from the animal 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 yellowjackets, invade honeybee nests and steal honey and/or brood.
The nests of some social wasps, such as hornets, are first constructed by the queen and reach about the size of a walnut before sterile female workers take over construction. The queen initially starts the nest by making a single layer or canopy and working outwards until she reaches the edges of the cavity. Beneath the canopy she constructs a stalk to which she can attach several cells; these cells are where the first eggs will be laid. The queen then continues to work outwards to the edges of the cavity after which she adds another tier. This process is repeated, each time adding a new tier until eventually enough female workers have been born and matured to take over construction of the nest leaving the queen to focus on reproduction. For this reason, the size of a nest is generally a good indicator of approximately how many female workers there are in the colony. Social wasp colonies often have populations exceeding several thousand female workers and at least one queen. Polistes and some related types of paper wasp do not construct their nests in tiers but rather in flat single combs.