Hunting wasp

Hunting wasps are members of various taxa of the insect order Hymenoptera. Their habits and affinities vary in many ways, but all practice parental care of their larvae in that they capture prey, usually insects, to feed their larvae. Whether solitary or social, most species construct some form of protection or nest in which they hide the prey and in which the larvae can feed and pupate in reasonable security. Most solitary hunting wasps sting their prey in such a manner as to paralyse it without killing it. As a result it remains fresh for the young to eat. In contrast carnivorous social wasps generally feed prey piecemeal to the larvae as soon as they bring it back to the colony, so there is no need for preservation of the material. A minority of solitary hunting wasps, such as certain Bembicinae, also butcher their prey before feeding it to the larvae.

Overview Hunting wasp is not a biological taxon, but rather describes certain ecological strategies that occur within the Hymenoptera. All hunting wasps are members of the Aculeata, within the Apocrita, but not all Aculeata are hunting wasps. Nor are the hunting wasps a single clade within the Aculeata; they almost certainly have evolved independently several times, sometimes probably several times within the same family. Some superfamilies of the Hymenoptera (e.g. Chrysidoidea) include a few taxa that might fairly be called hunting wasps, but no superfamily includes only hunting wasps.

Distinction between hunting wasps and "solitary wasps" In searching literature for "hunting wasps" it is prudent to include "solitary wasps" in the index terms. The two expressions have been used largely indiscriminately, especially in the very early days of modern entomology. Very few references to "hunting wasps" occur before about 1850, whereas references to "solitary wasps", though not plentiful, are not unusual. Strictly speaking, the terms "solitary wasp" and "hunting wasp" are not interchangeable. The term "solitary wasp" simply describes wasps that are not social. Not all solitary wasps are hunting wasps, nor are all hunting wasps solitary. For example, parasitic wasps are solitary, but not hunting (though it is not common practice to refer to them as solitary). In addition, Masarinae are solitary, but not hunting (cf. Euparagia). And some species e.g. the Vespa and Polistes are hunting wasps, but not solitary, and often eusocial.

Taxonomy and biology The taxa considered here are no more than a subset of those detailed in the article on the Apocrita. Nor are they listed here in the same sequence as in that article, but have been rearranged for convenience in discussing hunting wasp biology. In comparing the various hunting wasp taxa listed here, it is of fundamental importance to bear the following point in mind: supposing that members of one taxon exhibit adaptations to a given life history or biological strategy, and that another taxon has similar adaptations apparently more sophisticated, that need not in itself imply that either is descended from, or relevantly related to, the other. The reason for mentioning such taxa in close context is purely for suggestive illustration. Where the ancestral record of the more sophisticated strategy is unavailable, it often may be reasonable to observe that intermediate stages resembling the mechanisms of extant forms could be perfectly viable. For example, it seems plausible that a digger wasp such as a member of the Sphecidae might have had an ancestor that simply hid prey in available tunnels in much the same way that some Bethylidae still do, but it does not follow that the extant digger Sphecidae are descendants of the Bethylidae. Bearing this in mind, and that each of the superfamilies under discussion includes families other than those listed here, families that are in no way hunting wasps, consider the following, consulting the links and references for detailed discussion of the biology:

Superfamily Chrysidoidea Family Bethylidae The Chrysidoidea are not normally regarded as other than parasitoids, parasites, and kleptoparasites. Nor are they seriously considered as hunting wasps in this article, but some members of the family Bethylidae do have very suggestive patterns of reproductive biology. Though the details vary, these members of largely parasitoidal wasp taxa hunt their prey, paralyse them in various ways, including malaxation, drag them off, and conceal them before laying eggs on them. Many variations on the theme occur in the family. Observation of such members of the Bethylidae provides material of great evolutionary interest. It strongly suggests that various forms of parasitoidal behaviour within the Hymenoptera independently provided preadaptation for the development of typical hunting wasp behaviour. Superfamily Apoidea Although it had long been realised that bees were in essence a natural grouping of wasps that fed primarily on nectar and pollen, it took the development of molecular biology to demonstrate the actual grouping of true bees with the following families of definitive hunting wasps.

Family Ampulicidae These cockroach wasps are a popular example of a primitive mode of hunting wasp behaviour; they do not build a secure nest for their prey plus its egg, but conceal it in the most convenient crack or burrow, in which respect their behaviour resembles that of some of the Bethylidae.

Family Crabronidae A very large family with varied habits and a wide range of prey species. Crabronid species in some taxa concentrate on flies, others on bees, others on cicadas, but the overwhelming majority build tunnels, whether single or branched, with one or more larvae inside.

Family Sphecidae These are a widely varied family, including the digger wasps and mud daubers

Superfamily Vespoidea Family Pompilidae (spider wasps) Family Tiphiidae These are generally large wasps that hunt subterranean insects, usually beetle larvae. Commonly they do little to conceal the paralysed prey, but lay the egg on it underground.

Family Vespidae

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