The planarian Dugesia tigrina (Girard) was studied in the laboratory to assess its ability to prey on mosquito larvae. Different size ranges of planaria tested showed no significant differences in ability to consume larvae of mosquitoes. Dugesia tigrina more effectively reduced numbers of 2nd and 3rd instar mosquito larvae than 1st or 4th instar larvae or pupae. No significant mortality could be attributed solely to mucous secretions produced by the planaria; however, when planaria were present the secretions served as a mechanical aid to temporarily entrap larvae which were subsequently fed upon. Chironomid larvae were more easily fed upon than mosquito larvae and Gammerus sp. were captured less frequently than mosquitoes.