Aculeata

In Great Britain and/or Ireland:
Animal / parasitoid / ectoparasitoid
larva of Chrysis gracillima is ectoparasitoid of larva of Aculeata

Animal / kleptoparasite
larva of Miltogramma germari kleptoparasitises nest of Aculeata
Other: sole host/prey

Animal / kleptoparasite
larva of Miltogramma punctatum kleptoparasitises nest of Aculeata
Other: sole host/prey

Animal / parasite
Myrmosa atra parasitises nest of Aculeata

Animal / kleptoparasite
larva of Omalus puncticollis kleptoparasitises food store of Aculeata

Animal / kleptoparasite
larva of Pseudomalus auratus kleptoparasitises food store of Aculeata

Animal / kleptoparasite
larva of Smicromyrne rufipes kleptoparasitises food store of Aculeata

Animal / parasite
Trichrysis cyanea parasitises nest of Aculeata

This divisional name is retained because of the substantial biological literature published on the groups of Hymenoptera popularly called ants, wasps and bees. No clear-cut unambiguous criteria exist by which one can separate Aculeata from Parasitica for there are annectent forms in both divisions. ~In North America we recognize about equal numbers of valid species-level taxa in the Aculeata and Parasitica (or Terebrantia). However, there are comparatively few undescribed Aculeata, and subsequent revisionary studies probably will synonymize nearly as many taxa now considered to be valid as there will be new taxa described. Undoubtedly there are numerous undescribed small Parasitica. ~Aculeata occur in all major zoogeographic regions and on many of the oceanic islands; they are absent from Antarctica. Brothers (1975) recognizes 38 families of Aculeata. The majority occur in America north of Mexico except the Plumariidae, Scolebythidae, Loboscelidiidae and Fideliidae (sometimes placed in Megachilidae), all small families with very few species. The Cleptidae are here considered to be a subfamily of Chrysididae. The exotic Loboscelidiidae are best considered as an extremely aberrant subfamily of Chrysididae allied to the Amiseginae. Brothers considered the Crabronidae, here treated as a family, to be a subfamily of Larridae. ~Brothers recognized only three superfamilies of Aculeata, placing the scolioid, pompiloid and vespoid families in the Vespoidea, and consolidating the Sphecoidea and Apoidea under the former name. Further discussion of Brothers' arrangement will be found under appropriate superfamily headings. ~In general the Hymenoptera included in the Aculeata are characterized by conversion of the ovipositor to a stinging function only. The eggs are no longer exserted through the ovipositor as in most Parasitica but through an orifice anterior to it. The ovipositor with associated poison glands now serves several purposes, the temporary or permanent paralysis of the prey of wasps, as a defensive mechanism in bees and some ants, and as an offensive mechanism in some ants. However, annectent forms occur in some Proctotrupoidea of the Parasitica, and Bethyloidea and Scolioidea of the Aculeata. In many higher Parasitica the wing venation and thorax are much more reduced than in the Aculeata. ~Biologically the majority of Aculeata may be distinguished by their non-parasitic habits and the construction of nests for their young. Most higher wasps belonging to the Vespoidea, Pompiloidea and Sphecoidea are predaceous upon other arthropods and build nests which vary from simple to quite elaborate. A few species of Pompiloidea and Sphecoidea behave as parasitoids, paralyzing the prey, laying an egg upon it, and making no nest; the prey later recovers and leads a normal life until killed by the growing larva. Most of the vespoid Masaridae and all of the free-living bees have converted to a larval diet of pollen and nectar. Cleptoparasites or brood-parasites, whose larvae develop in the nests of other wasps or bees, have evolved independently a number of times in all aculeate superfamilies. However, these biological distinctions break down in most of the more primitive wasps belonging to the Bethyloidea and Scolioidea. Many of these behave as true parasitoids in that the larval prey may be only temporarily paralyzed, occasionally several eggs may be laid on a single prey larva, and frequently no nest whatever is made, the prey being left in situ, or at most a crude cell may be constructed around the subterranean prey as in most Tiphiidae and Scoliidae. Parasitism of the egg stage of the host is known only among the Amiseginae (Chrysididae). Polyembryony is unknown, but parthenogenesis occurs in some Aculeata. Usually this is of the facultative kind as is found in social insects such as some ants, vespid wasps and honeybees. It may be obligate in some aculeates, such as the tiphiid wasp Methocha and some species of the bee genus Ceratina, where males are rare or unknown. ~The simplest kind of nest among the aculeates is made by the wasp dragging the paralyzed prey into a crevice in or above ground or back into the prey's burrow; the opening is usually sealed off by particles of the substrate to make a crude cell. A second type of nest is also made in a pre-existing cavity, such as borings of beetle larvae in wood or twigs, or in old insect galls or abandoned mud cells. The nest in this second type may be unicellular as in the first kind of nest, or it may consist of a linear series of cells, each cell separated from its neighbor by a partition of mud, wood chips, resin, masticated plant leaves, or other substances. A third kind of nest is excavated by the wasp or bee in the ground, in rotten wood, or in the soft pith of such shrubs as sumac and elderberry. The subterranean nests are frequently unicellular but multicellular nests in the ground, rotten wood or pith may have the individual cells arranged in a linear series or in clusters with the individual cells sealed by a partition or closing plug of the substrate. Occasionally a mud turret may be constructed over the entrance of subterranean nests. Next, there are the nests constructed entirely from foreign materials. Usually these are above ground although some Vespidae and Bombinae have subterranean nests. The nests of solitary species may be made of mud, or a mixture of resin and pebbles, with the cells arranged in parallel tubes, or in clusters or with separate but adjacent cells; some exotic social Vespidae make a mud envelope around combs of hexagonal cells. A number of social species make paper or carton nests in which the nesting material consists of masticated wood fibers, bark or rotten wood. Finally, there is the complex nest of the honeybees constructed from wax secreted from glands in the abdomen of workers. ~Aculeate larvae are normally cannibalistic if they come in contact accidentally. This tendency is prevented in multicellular nests by the existence of partitions separating adjacent larvae. However, some species make brood cells in which several larvae develop amicably without the occurrence of cannibalism. Such nests have been reported for a few North American Isodontia (Sphecidae) and Megachile (Megachilidae), and for many exotic Allodapini (Anthophoridae). ~True sociality (eusociality) has arisen independently several times in the higher aculeates, the Formicoidea, Vespoidea, Sphecoidea and Apoidea. All of the ants are eusocial or are social parasites of other ants, but the majority of wasps and bees are solitary species. Wilson (1971) considers that eusocial insects must possess three traits: "individuals of the same species cooperate in caring for the young; there is a reproductive division of labor, with more or less sterile individuals working on behalf of fecund individuals; and there is an overlap of at least two generations in life stages capable of contributing to colony labor, so that offspring assist parents during some period of their life." Presocial insects exhibit one or two of the above traits. Solitary species have none of these traits. ~Most solitary aculeates practice mass provisioning, that is, the egg is laid and a store of food is placed in the cell with it, then the cell is closed; in many species the store of food is provided before oviposition. Some sphecoid wasps, such as many Bembicinae (Nyssonidae), have taken the first step toward subsocial status by adopting progressive provisioning. This behavior is characterized by placing the egg on a single prey specimen and not furnishing additional prey until the egg has hatched or by the hatching of the egg before any food is provided; after hatching the larva is fed daily or at intervals as required. Other aculeates, e.g., Moniaecera (Crabronidae), some Andrena (Andrenidae) and Exomalopsis (Anthophoridae), have achieved the higher level of communal status, in which several females use a common burrow entrance but presumably maintain separate cells. A higher level of presocial behavior (quasisocial) is found rarely in some exotic bees where two or more gravid females of the same generation cooperatively construct and provision the cells. Some of our Halictidae have attained the semisocial stage which is similar to the quasisocial except that unmated females of the same generation associate with a gravid female or females and care for the larvae of the latter. A semisocial colony may evolve into a primitive eusocial colony as happens later in the season in some Augochlorella nests when the colony becomes monogynous and only the workers forage for pollen. Another stage toward the eusocial is the subsocial in which one female cares for her own larvae as in many Allodapini (Anthophoridae) and young nests of Bombus (Apidae); such a colony may later become truly eusocial as happens when the first brood of Bombus workers ecloses and takes over the foraging activities previously performed by the queen.

Aculeata is a subclade 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. It is theorized that the possession of a venomous sting was important in the repeated evolution of eusociality within Hymenoptera.

The oldest aculeates are known from the Late Jurassic Karabastau Formation of Kazakhstan, represented by the family Bethylonymidae, which may be para or polyphyletic.