Light weight net jackets treated with N,N-diethyl -m-toluamide (Deet) were field tested in Florida, South Carolina, and Puerto Rico against 4 species of biting midge, Culicoides furens (Poey), Cu. mississippiensis Hoffman, Cu. hollensis (Melander and Brues), and Cu. barbosai Wirth and Blanton. The Deet-treated jacket provided 98 to 99% protection against all species except Cu. barbosai. It gave only about 59% protection against Cu. barbosai. As many species as possible should be tested in evaluating personal protection methods.