Southern Ontario survey of eyeworms, Thelazia gulosa and Thelazia lacrymalis in cattle and larvae of Thelazia spp. in the face fly, Musca autumnalis.

An eight month survey of bovine eyes from an abattoir in southern Ontario revealed the presence of the eyeworms Thelazia gulosa and T. lacrymalis in 32% of the cattle. In the same area, 3% of the natural population of face flies (Musca autumnalis) harbored larval eyeworms. A review of the literature is provided.