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| Insects of Britain and Ireland: the families of Hymenoptera |
Stem Sawflies.
Adults small to large; 4–10 mm long (mostly), or 11–18 mm long (Hartigia).
Head. Antennal segments 16–30.
Thorax. Pronotum more or less straight at the back. Cenchri absent. Fore-wings with the venation well developed. Hind tibiae without specialised spurs.
Abdomen. The abdomen broadly sessile at its base, without a marked constriction (with a slight constriction only). The gaster concolorous, or colour-patterned; when concolorous, black or dark coloured; when patterned, black-and-yellow or brown-and-yellow. Ovipositor of females not visibly protruding.
Larvae. Larvae legless or the legs vestigial (the legs vestigial, and prolegs lacking); phytophagous (boring in stems, with Hartigia and Janus on dicot trees and Rosaceae, the rest on Gramineae and sometimes damaging cereal crops).
General comments. Slender insects, the body more or less cylindrical or bilaterally compressed.
British representation. Species in Britain 12; Calameuta, Cephus, Hartigia, Janus, Trachelus.
Classification. Suborder Symphyta; Superfamily Cephoidea.
Illustrations. • Calamenta, Cephus, Janus, Trachelus (Cameron III). 3, Janus femoratus (Curtis); 4 and 5, Cephus pygmaeus (Linn.), female and male, respectively; 6, Cephus cultratus Eversmann, female; 7 and 8, Calamenta pallipes (Klug.), female and male, respectively; 9, Trachelus tabidus (Fabr.), female; 10, Cephus linearis (Schrank), female. From Cameron (1890). • Janus femoratus (Curtis), Yellow-thighed Cephus: B. Ent. 301. • Janus femoratus (detail): B. Ent. 301. • Janus femoratus (dissections): B. Ent. 301. • Janus femoratus (B. Ent. 301, legend+text. Seemingly the original Curtis description of femoratus, since tranferred to Janus. • Janus femoratus: B. Ent. 301, text cont.. • Janus femoratus (Cameron II, vii). female. 1a, mandibles; 1b, labium; 1c, maxillary palpus. • Calamenta filiformis (Cameron II, vii). female. 3a, maxillary palpus. 3b, ovipositor: a, cerci; b, oblong plate; c, attachment of the latter; d, saw; e, triangular plate; f, hypopygium. • Hartigia linearis (Cameron II, vii). male. 2a, mandibles; 2b, maxillary palpus; 2c, labium.
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 Hymenoptera. Version: 14th April 2022. delta-intkey.com’.
