isolated in glacial refugia during the last glaciation, probably in Iberia for C. halophilus and in northern Italy for C. hederae. It is further postulated that the new species were probably expanding their ranges to exploit new populations of their foodplants and this can still be seen in the colonisation of southern Britain by C. hederae in the 1990s and its expansion in Bavaria. This hypothesis is further supported by the evidence that E. cruciger only parasitizes C. hederae south of the Alps and probably represents a localised and specialised "race" of E. cruciger which has not been able to expand its distribution as its host has done. References Colletidae Hymenoptera of Europe Bees described in 1758 Taxa named by Carl Linnaeus