Food Plant: Sempervivum tectorum (Common houseleek), S. arachnoideum (Cobweb houseleek) and S. montanum (Mountain houseleek)

Mine: May-June, August-September

Notes: The outer leaves of rosettes of affected plants become greyish or brownish-green (as shown) and then become limp and dry up. The larva (two larvae are shown) exits a leaf, near its base, to move to another leaf to feed or pupate in the soil leaving a hole, . First discovered in Surrey in 2006, presumably from imported plants (Collins & Halstead (2008)). It is slowly spreading in the UK, reaching Norfolk in 2013.

Data: 2008, RHS Wisley, Surrey, VC17

Image:© RHS/Andrew Halstead

References:
Collins, G & Halstead, AJ (2008),Cheilosia caerulescens (Meigen, 1822) (Diptera, Syrphidae) new to Britain Dipterists Digest, 15(1), 23-26