Ovipositor in the context of Cola-nut gall

A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. The wasps do not constitute a clade, a complete natural group with a single ancestor, as bees and ants are deeply nested within the wasps, having evolved from wasp ancestors. Wasps that are members of the clade Aculeata can sting their prey.

The most commonly known wasps, such as yellowjackets and hornets, are in the family Vespidae and are eusocial, living together in a nest with an egg-laying queen and non-reproducing workers. Eusociality is favoured by the unusual haplodiploid system of sex determination in Hymenoptera, as it makes sisters exceptionally closely related to each other. However, the majority of wasp species are solitary, with each adult female living and breeding independently. Females typically have an ovipositor for laying eggs in or near a food source for the larvae, though in the Aculeata the ovipositor is often modified instead into a sting used for defense or prey capture.

Hymenoptera is a large order of insects, comprising the sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are parasitic. Females typically have a special ovipositor for inserting eggs into hosts or places that are otherwise inaccessible. This ovipositor is often modified into a stinger. The young develop through holometabolism (complete metamorphosis)—that is, they have a wormlike larval stage and an inactive pupal stage before they reach adulthood.

Sawflies are wasp-like insects that are in the suborder Symphyta within the order Hymenoptera. The common name comes from the saw-like appearance of the ovipositor, which females use to cut into the plants where they lay their eggs. The name is associated especially with the Tenthredinoidea, by far the largest superfamily in the suborder, with about 7,000 known species in the entire suborder. There are 8,000 described species in more than 800 genera.

Despite their given taxonomic rank of suborder, Symphyta is a paraphyletic group, consisting of several basal groups within the order Hymenoptera, with each one rooted inside the previous group; the various superfamilies of insects called "sawfly" do form a natural group or clade, but this clade also includes the Apocrita – the ants, bees, and wasps – which are not considered sawflies. The primary distinction between sawflies and the Apocrita is that the adult sawflies (the imago) lack a "wasp waist" or petiole; the segments connecting the abdomen and the thorax smoothly transition between the two (leading to their scientific name). Sawflies first appeared 250 million years ago in the Triassic. The oldest superfamily, the Xyeloidea, is still extant today. Over 200 million years ago, a lineage of sawflies evolved a parasitoid lifestyle, with carnivorous larvae that ate the eggs or larvae of other insects. Sawflies are distributed globally, though they are more diverse in the northernmost hemispheres.

Aculeata is an infraorder of Hymenoptera containing ants, bees, and stinging wasps. The name is a reference to the defining feature of the group, which is the modification of the ovipositor into a stinger. However, many members of the group cannot sting, either retaining the ovipositor, or having lost it altogether. A large part of the clade is parasitic.

This group includes all of the eusocial Hymenopterans.

Cockroaches (or roaches) are insects belonging to the order Blattodea (Blattaria). About 30 cockroach species out of 4,600 are associated with human habitats. Some species are well-known pests.

Modern cockroaches are an ancient group that first appeared during the Late Jurassic, with their ancestors, known as "roachoids", likely originating during the Carboniferous period around 320 million years ago. Those early ancestors, however, lacked the internal ovipositors of modern roaches. Cockroaches are somewhat generalized insects lacking special adaptations (such as the sucking mouthparts of aphids and other true bugs); they have chewing mouthparts and are probably among the most primitive of living Neopteran insects. They are common and hardy insects capable of tolerating a wide range of climates, from Arctic cold to tropical heat. Tropical cockroaches are often much larger than temperate species.

Crickets are orthopteran insects which are related to bush crickets and, more distantly, to grasshoppers. In older literature, such as Imms, "crickets" were placed at the family level (i.e. Gryllidae), but contemporary authorities including Otte now place them in the superfamily Grylloidea. The word has been used in combination to describe more distantly related taxa in the suborder Ensifera, such as king crickets and mole crickets.

Crickets have mainly cylindrically shaped bodies, round heads, and long antennae. Behind the head is a smooth, robust pronotum. The abdomen ends in a pair of long cerci; females have a long, cylindrical ovipositor. Diagnostic features include legs with 3-segmented tarsi; as with many Orthoptera, the hind legs have enlarged femora, providing power for jumping. The front wings are adapted as tough, leathery elytra, and some crickets chirp by rubbing parts of these together. The hind wings are membranous and folded when not in use for flight; many species, however, are flightless. The largest members of the family are the bull crickets, Brachytrupes, which are up to 5 cm (2 in) long.

"Roachoids", also known as "Roachids", "Blattoids" or Eoblattodea, are members of the stem group of Dictyoptera (the group containing modern cockroaches, termites and praying mantises). They generally resemble cockroaches, but most members, unlike modern dictyopterans, have generally long external ovipositors, and are thought not to have laid ootheca like modern dictyopterans.

Dictyoptera (from Greek δίκτυον diktyon "net" and πτερόν pteron "wing") is an insect superorder that includes two extant orders of polyneopterous insects: the order Blattodea (termites and cockroaches together) and the order Mantodea (mantises). All modern Dictyoptera have short ovipositors and typically lay oothecae. The oldest fossils of Dictyoptera from the Late Carboniferous, referred to as "roachoids" have long ovipositors and did not lay oothecae. The oldest modern oothecae-laying dictyopterans date to the Late Triassic.

Megarhyssa macrurus, also known as the long-tailed giant ichneumonid wasp or long-tailed giant ichneumon wasp, is a species of large ichneumon wasp. It is a parasitoid, notable for its extremely long ovipositor which it uses to deposit an egg into a tunnel in dead wood bored by its host, the larva of a similarly large species of horntail.