The ecology and rapid spread of the terrestrial slug Boettgerilla pallens in Europe with reference to its recent discovery in North America

The terrestrial slug Boettgerilla pallens Simroth, 1912, is reported from t wo sites on Vancouver Island, British Columbia, the first records for this Palaearctic species in America. This paper describes how to recognize the s pecies, and summarizes European studies of its ecology. It is unusually wor mlike in appearance, lives mostly underground, and occurs in a very wide ra nge of habitats. This century the species has spread remarkably far and fas t across Europe from the Caucasus. This is demonstrated by a table of first occurrences in each country, and by three case studies of spread within Gr eat Britain, Belgium, and north-west Austria. We predict that it will sprea d rapidly in North America, and may already occur more widely, but there is no evidence that it will become an important pest.