The Cephidae are slender, long bodied sawflies. They are characterised by elongate antennae with between sixteen and thirty segments. The mesonotum does not extend in front of the tegulae and the hind margin of the pronotum is almost straight or only deviating from straight by a strongly obtuse angle. The Cephidae are unique in lacking cenchri and being slightly restricted dorsoventrally between the first and second abdominal segments. The male genitalia are orthandrous such that the male mounts the female as opposed to mating back to back. Cephidae produce only one generation per annum.
Larval Cephidae feed inside the stems of grasses, roses or in some cases tree twigs. They are referred to as stem borers and there morphology is reduced in that they lack any abdominal legs and vestigial thoracic legs. The larvae cocoon within the plant stem. Cephidae that bore into grasses can be serious pests in cereal crops.
Cephidae are predominantly a Eurasian family of about one hundred species falling within thirteen genera. In Britain there are fourteen species within five genera: Calameuta, Cephus, Trachelus, Janus, and Phylloecus (formerly Hartigia). The five genera fall into two tribes: the Cephini and the Hartigiini.
The Cephini (Calameuta, Cephus and Trachelus) have the basal metatarsomere clearly shorter than the combined length of the following three tarsomeres. The maxillary palps have the sixth (apical) segment much longer than the fourth segment and it is mounted to the apex of the fifth segment.
The Hartigiini (Janus and Phylloecus) have the basal metatarsomere much longer than the combined length of the following three tarsomeres. The maxillary palps have the sixth (apical) segment either subequal to the forth, or it is mounted to the side of the fifth segment.
Tribe Cephini Newman, 1834
Genus Calameuta Konow, 1896
Calameuta filiformis (Eversmann, 1847)
Calameuta pallipes (Klug, 1803)
Genus Cephus Latreille, 1802
Cephus nigrinus Thomson, 1871
Cephus pygmeus (Linnaeus, 1767)
Cephus spinipes (Panzer, 1800)
Genus Trachelus Jurine, 1807
Trachelus tabidus (Fabricius, 1775)
Trachelus troglodyta (Fabricius, 1787)
Tribe Hartigiini Enslin, 1914
Genus Janus Stephens, 1829
Janus compressus (Fabricius, 1793)
Janus cynosbati (Linnaeus, 1758)
Janus luteipes (Lepeletier, 1823)
Genus Phylloecus Newman, 1838
Phylloecus faunus Newman, 1838
Phylloecus linearis (Schrank, 1781)
Phylloecus niger (M. Harris, 1779)
Phylloecus xanthostoma (Eversmann, 1847)
Benson, R.B., 1952. Handbooks for the Identification of British Insects. Hymenoptera, Symphyta, Vol 6, Section 2(a), Royal Entomological Society, London
Goulet, H., 1876. The genera and subgenera of the sawflies of Canada and Alaska: Hymenoptera: Symphyta. The Insects and Arachnids of Canada (Part 20). Agriculture Canada Publication.
Liston A, Knight G, Sheppard D, Broad G, Livermore L (2014) Checklist of British and Irish Hymenoptera - Sawflies, ‘Symphyta’. Biodiversity Data Journal 2: e1168. https://doi.org/10.3897/BDJ.2.e1168