Curculio betulae (Stephens, 1831)

This species is locally common from the Mediterranean north to the UK and middle provinces of Fennoscandia, it extends east through the entire northern Palaearctic region to the far east of Russia and Japan but is generally absent from southern regions including China and North Africa. In the UK it occurs sporadically across central and southeast England and Wales and there are scattered records from western Ireland; adults may sometimes occur in numbers where found but it is otherwise very local and scarce. Adults occur from June until (exceptionally) October, peaking in abundance during July, but specimens occasionally occur following mild spells in January or February, typical habitats include wet forest margins, carr, peat bogs and drier parts of fens and marshes. In the UK the usual host plant is Birch, Betula pendula Roth, and it is only occasionally found on Alder but through much of northern Europe the usual hosts are Grey Alder, Alnus incana (L.), and Black Alder, A. glutinosa (L.) and it only occasionally occurs on Birch and, much less frequently, adults are sometimes found on willows, Salix L., and various species of Prunus L. including Blackthorn and cherry. Mating occurs early in the season following a period of feeding on host foliage and females lay groups of three or four eggs in developing female catkins. Larvae feed into the summer, passing through three instars and completely hollowing-out the catkins, when fully-grown they leave the catkin, fall to the ground and burrow a few cm into the soil where they construct a pupal chamber; the pupal stage is probably brief as adults are sometimes found during the winter but the majority will remain in situ until the late spring, emerging when the catkins are at the right stage of development for oviposition. Adults are usually found by chance sweeping or beating suitable foliage.