Though present much earlier in small numbers, the first outbreaks of infestation were reported in Wales in 1972. The species rapidly spread to larch plantations in England and Scotland. The species mates at ground level shortly after emerging from leaf litter in the spring. Mated females climb tree trunks or fly to the crown of the trees to lay eggs. Adult Cephalcia lariciphila are black with off-white markings on the head, thorax and sides of the abdomen. The tibia and some basal antennal segments are reddish.
Larvae spin a silk tube and feed on the young shoots. When full grown (around July) the larvae drop or decend on silk and burrow to where the leaf litter meets the underlying soil. They overwinter as a prepupa and pupate in early spring.
Size: approx. 10 - 12mm
Distribution: England, Scotland, Wales
Flight period: Univoltine, April to June
Plant associations: Larix spp (larches)
The National Biodiversity Network records are shown on the map below. (See terms and conditions)
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. https://doi.org/10.3897/BDJ.2.e1168
Billany D J, Brown R M (1980) The Web-spinning Larch Sawfly, Cephalcia lariciphila Wachtl. (Hymenoptera: Pamphiliidae) A New Pest of Larix in England and Wales. Forestry 53(1)