The geographical distribution of tapeworms of the field vole Microtus agrestis in Fennoscandia. All species except Hymenolepis (s.l.) asymmetrica (Hymenolepididae) represent the family Anoplocephalidae. Grey symbols, species absent; black symbols, species present. The number of voles examined for helminths in each locality varies considerably, but is usually more than ten (several hundred in Kilpisjärvi and Pallasjärvi in western Finnish Lapland).