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| Insects of Britain and Ireland: the families of Coleoptera |
General appearance. 1.5–3.5 mm long.
Detailed morphology. Beetles without a rostrum. Eyes present; coarsely facetted (very granular in appearance). The maxillary palps not especially elongated. Antennae very short to short; 4 segmented (Elenchidae), or 6 segmented (Stylopidae), or 7 segmented (Halictophagidae); without a much-elongated scape. Antennal scape not swollen. Antennae with lateral extensions on the third segment only in Elenchidae and Stylopidae, or pectinate in Halictophagidae.
Scutellum conspicuous. The prosternal process complete. The fore-leg coxae countersunk in ‘procoxal cavities’. Hind-leg coxae without the steep transverse declivity characteristic of Dryopoidea. The tarsi with 2–4 segments; without ‘hidden’ segments.
Elytra present (but vestigial, in males), or absent (females); those of males short, exposing several terminal abdominal tergites (analagous to the halteres of Diptera).
Adult habitat, ecology. Land-dwellers; not predacious.
Larvae. Larvae late instars parasitic (on insects from many orders, but especially Hymenoptera and Hemiptera).
Representation in Britain and Ireland, and worldwide. About 600 species worldwide (in 10 families). About 20 species in Britain; genera in Britain 4 (in the families Elenchidae, Halictophagidae and Stylopidae); Elenchus, Halictophagus, Stylops. E.g., Elenchus tenuicornis, Halictophagus curtisi (Lulworth Stylopid), Stylops dalei (Dale's Stylopid: but see the recently ‘corrected’ specific epithet, dalii!).
General comments. A small Order, sometimes associated taxonomically with the Coleoptera. Males free-living and actively flying; females larviform, usually parasitic, in puparia within the hosts. The male’s legs are unique among insects in lacking trochanters. A more detailed description of the Order is available in the accompanying, ‘Orders’ data set.
Illustrations. • Elenchus tenuicornis (B. Ent. 385). • Elenchus tenuicornis: B. Ent. 385, legend+text. • Halictophagus curtisii (Lulworth Stylopid: B. Ent. 433). • Halictophagus curtisi (details, B. Ent. 433). • Halictophagus curtisi: B. Ent. 433, legend+text. • Stylops dalei (Dale’s Stylopid: B. Ent. 226). • Stylops dalei: B. Ent. 226, legend+text. • Stylops dalei (Dale’s Stylopid: B. Ent. 226). • Stylops dalei: B. Ent. 226, legend+text. • Stylops, Elenchus and Halictophagus (with Coleoptera-Scolytidae): Fowler 5, 180 (1891). COLEOPTERA-Scolytidae. 1, Trypodendron signatum. 2–3, Xyleborus dispar, male and female; 4–5, Xyleborus dryographus, male and female. 6, Platypus cylindricus. STREPSIPTERA-Stylopidae. 7, Stylops dalii. 7a, larvae inhabiting the abdomens of living Andrenidae, showing their heads exserted between the segments; 7b, a larva, extracted; 7c, pupa; 7d, tarsus. 8, Stylops melittae. STREPSIPTERA-Elenchidae. 9, Elenchus tenuicornis. STREPSIPTERA-Halictophagidae. 10, Halictophagus curtisii; 10a, antenna; 10b, posterior tarsus. From Fowler's plate, with the names from the original legend (q.v.) updated. • Fowler 5, 180 (1891): original legend..
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, 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. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. Insects of Britain and Ireland: the families of Coleoptera. Version: 27th July 2019. delta-intkey.com’.
