Insects of Britain and Ireland: orders

DELTA home

L. Watson and M. J. Dallwitz



Adult insects. The neotenic, larviform females parasitic (the diet of males being unknown); the females parasitising invertebrates only (being permanent, entomophagous endoparasites). Minute to small; capable of flight (males), or flightless (females); the males only with one pair of propellant wings (the hindwings). Head hypognathous (males), or prognathous to hypognathous (females). Mouthparts quite well developed (though somewhat reduced: the mandibles broad and scimitar-shaped, the maxillae reduced to 2-segmented palpi, and the labial palpi absent); more or less of the biting type; not piercing; highly modified (much reduced from the normal biting type). Antennae present (in the males), or absent (in the females); in the males, relatively conspicuous; complex (ostensibly bifircate, because of the conspicuously flabellate third segment); 4–7 segmented. Ocelli 0. Wings of the males two, or four (if the much reduced and haltere-like or elytriform fore-wings are interpreted as such); markedly differently textured in the two pairs. Fore-wings much reduced. Hind-wings very much larger than the fore-wings; much markedly broader than the fore-wings; folded in repose. Wings with few cross-veins (greatly reduced); more or less naked. Wings of the resting insect closed and directed backwards. Thoracic legs present (in the males), or absent (in females). Tarsi 4 segmented, or 5 segmented. Abdomen not conspicuously appendaged; lacking clearly visible cerci; apparently (8–)9(–10) segmented (1 fused with the metathorax, one or two more partly concealed beneath the post-scutellum).

Larvae. Larvae clandestine feeders; (endo-) parasitic (in all but the well differentiated, free-living, actively host-seeking first instar, which moults to become apodous after entering the host); without segmented thoracic legs; without ventral abdominal prolegs; without anal prolegs. Development of larva into adult involving marked metamorphosis; endopterygote; involving a pupal stage (males), or not involving a pupal stage (the pupal stage being suppressed in the females).

Pupae. Pupae of males without articulated mandibles; with free appendages.

Classification. Subclass Pterygota; Division Endopterygota.

British representation. Elenchidae, Halictophagidae, Stylopidae; genera 5; 18 species.

Special features. Males actively flying, having fore-wings reduced to knobbed, haltere-like structures and large, membranous hind-wings; females larviform and confined to puparia inside hymenopterous or hemipterous hosts. The wingless adults of the females larviform, with the thorax clearly segmented.

Illustrations. • Elenchus Curtis, Elenchus tenuicornis (W. Kirby): B. Ent. 385. • Elenchus, E. tenuicornis: B. Ent. 385, legend+text. • Elenchus, E. tenuicornis: B. Ent. 385, text cont.. • Halictophagus curtisii Dale in Curtis (Lulworth Stylopid: B. Ent. 433). • Halictophagus curtisii (details, B. Ent. 433). • Halictophagus curtisii: B. Ent. 433, legend+text. • Halictophagus curtisii: B. Ent. 433, text cont.. • Stylops dalii Curtis (Dale’s Stylopid: B. Ent. 226). • Stylops dalii: B. Ent. 226, legend+text. • Stylops dalii: B. Ent. 226, text cont.. • Stylops, female and larva (Lubbock 1890). adult female. larva. • Stylops, Elenchus and Halictophagus (with Coleoptera-Scolytidae): Fowler 5, 180 (1891). • Fowler 5, 180 (1891): legend. • Stylops melittae: Stevens 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. Insects of Britain and Ireland: orders. Version: 16th May 2016.’.