British Insects: the Families of Hymenoptera


L. Watson and M. J. Dallwitz


Chalcid Wasps.

Adults minute to small; minute to small, but the ovipositor often much longer than the body. Insects associated with plant galls (mostly), or not associated with galls.

Head. Antennae geniculate.

Thorax. Pronotum more or less straight at the back; short, not extending back to the tegulae. The mesepisternum not enlarged to obscure the mesepimeron (and the mid-tibial spur rarely larger than the hind one). Cenchri absent. Wings present (males of some species), or absent; not folding longitudinally. Fore-wings without a pterostigma; with very reduced venation (reduced to a proximal submarginal vein, which becomes marginal distally before giving off the stigmal vein); combining greatly reduced venation with a conspicuous, blind-ending stigmal vein. Closed fore-wing cells 0. Submarginal cells 0. Discoidal cells 0. Hind-wings without closed cells. The hind coxae five to six times the size of the front ones. Fore tibiae with a curved spur. Hind femur toothed below, or not toothed below; with a clear trochantellus. Hind femur simple or 1-toothed beneath. Hind tibiae conspicuously curved around the femora, or not curved around the femora; without specialised spurs. Tarsi 5 segmented.

Abdomen. The abdomen with a marked basal constriction. Ovipositor of females usually visibly protruding; adapted for piercing.

Larvae. Larvae with segmented legs; phytophagous, or parasitic on hosts selected by the mother (including parasites and hyper-parasites of other hymenopterous gall-inducers), or parasitic on hosts selected by the mother and predacious (some occuring in nests of bees and wasps); when gall-associated (i.e., usually), primary inducers of galls (a few), or parasitic on other gall occupants, or predacious on other gall occupants (mostly being parasites of gallicolous insects).

British representation. Species in Britain about 75; Cryptopristus, Diomorus, Glyphomerus, Megastigmus, Monodontomerus, Pseudotorymus, Torymus (with most of the species referable to Monodontomerus, Megastigmus or Torymus).

Classification. Suborder Apocrita; Series Parasitica; Superfamily Chalcidoidea.

Illustrations. • Torymus nobilis (Cynips Parasite): B. Ent. 552. • Torymus nobilis, detail: B. Ent. 552. • Torymus nobilis, dissections: B. Ent. 552. • Torymus nobilis: B. Ent. 552, legend+text. • Torymus nobilis: : B. Ent. 552, text cont.. • Megastigmus dorsalis (female) and Callimome varians: Stephens 1846.

To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. British insects: the families of Hymenoptera. Version: 1st January 2012.’.