Agelastica alni

Description

Agelastica alni, the alder leaf beetle, is a species of leaf beetle (Chrysomelidae) in the genus Agelastica. Agelastica alni is distributed in Europe, the Caucasuses, Siberia, north-eastern Kazakhstan, and in the 19th century was introduced to the United States (Kolk & Starzyk, 1996). The beetle and the beetle's larvae host on the grey or speckled alder (Alnus incana) and to a lesser extent black alder (Alnus glutinosa), but will be found on hazel, birch and/or hornbeam if there is a shortage of food. Causing large holes and gaps from the end of April onwards, which are produced by the larvae in the first two stages, but the main damage is only produced by larvae in the third stage. Previously rare, and considered extinct in the UK, since being found in Manchester in 2004 it appears to be on the increase in the North West of England. The beetle has since been spreading and found in North Wales in 2018.