Cacopsylla ulmi

Description

Cacopsylla ulmi is an insect of the Psyllidae family. It mainly feeds on Elm. Cacopsylla ulmi is a widespread species in Europe, including Britain and the Balkans. Adults are 3.6–4.3 mm long. The head is 1–1.01 mm wide, with a vertex which is 0.5 mm wide and 0.24–0.28 mm long. The genal cones are laterally somewhat concave, and 0.25 mm long (Fig. 1). Antennae are 1.89–2.0 mm. Forewings are 3.5 mm long and 1.4 mm wide. The insect was first recorded in Britain by Elwes, who found a line of European White Elms Ulmus laevis in Devon infested with the insect in 1908, though without apparent detriment to the hosts. Elwes determined that the imagines did not hibernate, rather laid their eggs in autumn, suggesting to him a foreign origin. It was the first and only occasion Elwes encountered the insect in Britain. Richens later observed that U. laevis was the only elm afflicted by C. ulmi at Kew.