Family Blasticotomidae - Fern-borer Sawflies

The Blasticotomidae are characterised by the four segmented antennae which ressemble those of the Argidae in that the third antennal segment is long and cylindrical but differ in having a tiny fourth conical segment apically. This fourth segment is occasionally obsolete. The shape of cell 1M of the forewing is unique in that the apical vein is domed outwards. The stigma is bulbous such that it is almost semicircular.

Blasticotomidae is a small family of two genera and about 12 species confined to the temperate areas of the Palaeartic region. All but one species occur in East Asia. The European species, Blasticotoma filiceti, is rare throughout its range.

Larvae bore the rachis of ferns to create an open ended tunnel. Active tunnels are indicated by the presence of a sticky, frothy mass at the entrance produced by the larva as it feeds on the plant sap. The froth is apparently attractive to ants.

Species list:

Genus Blasticotoma Klug, 1834

Blasticotoma filiceti Klug, 1834


Benson, R.B., 1952. Handbooks for the Identification of British Insects. Hymenoptera, Symphyta, Vol 6, Section 2(a-c), Royal Entomological Society, London

Liston A, Knight G, Sheppard D, Broad G, Livermore L (2014) Checklist of British and Irish Hymenoptera - Sawflies, ‘Symphyta’. Biodiversity Data Journal 2: e1168.