Wasps On The Playground
Wasps can be really dangerous and scary!
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 parasitizes it, making wasps critically important in natural control of their numbers, or natural biocontrol. 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 suborder Symphyta, known commonly as sawflies, differ from members of Apocrita by lacking a sting, and having a broader connection between the mesosoma and metasoma. In addition to this, Symphyta larvae are mostly herbivorous and “caterpillarlike”, whereas those of Apocrita are largely predatory or parasitoids.
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 yellowjackets (Vespula and Dolichovespula) and hornets (Vespa); in many countries outside of the Western Hemisphere, the vernacular usage of wasp is even further restricted to apply strictly to yellowjackets.
The various species of wasps fall into one of two main categories: solitary wasps and social wasps. Adult solitary 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 strong and build nests—but in some cases not all of the colony can reproduce. In the more advanced species, just the wasp queen and male wasps can mate, whilst the majority of the colony is made up of sterile female workers.
The following characteristics are present in most wasps:
# Two pairs of wings (except wingless or brachypterous forms in all female Mutillidae, Bradynobaenidae, many male Agaonidae, many female Ichneumonidae, Braconidae, Tiphiidae, Scelionidae, Rhopalosomatidae, Eupelmidae, and various other families).
# An ovipositor, or stinger (which is only present in females because it derives from the ovipositor, a female sex organ).
# Few or no thickened hairs (in contrast to bees); except Mutillidae, Bradynobaenidae, Scoliidae.
# Nearly all wasps are terrestrial; only a few specialized parasitic groups are aquatic.
# Predators or parasitoids, mostly on other terrestrial insects; most species of Pompilidae (e.g. tarantula hawks), specialize in using spiders as prey, and various parasitic wasps use spiders or other arachnids as reproductive hosts.
Wasps are critically important in natural biocontrol. Almost every pest insect species has at least one wasp species that is a predator or parasite upon it. Parasitic wasps are also increasingly used in agricultural pest control. Wasps also constitute an important part of the food chain.
In wasps, as in other Hymenoptera, sexes are significantly genetically different. Females have a diploid number of chromosomes and come about from fertilized eggs. Males, in contrast, have a haploid number of chromosomes and develop from an unfertilized egg. Wasps store sperm inside their body and control its release for each individual 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.
Anatomy and gender
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 genders 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 plumose hairs.
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