Alder beetle (Agelastica alni)

The Alder leaf beetle is a 7-8 mm long dark metallic blue leaf beetle that feeds on alder (Alnus) and is occasionally found on other deciduous trees such as beech (Fagus sylvatica), hazel (Corylus) and hornbeam (Carpinus betulus).

It overwinters as adults, which emerge in the spring, sometimes in large numbers.

Seen in Osterly Park in August 2020