A laboratory study on the face fly reported herein was conducted at Blacksburg, Virginia, from July through September, 1962, to ascertain the biology of each stage of the life cycle, and to determine the relationship of certain environmental factors on the fly activity under laboratory conditions. Morphological descriptions of each life stage were made in order to distinguish this insect from other related muscoid flies. Temperature and humidity were found to be two essential environmental factors which influenced the development and activities of the face fly. Rate of development in each stage under different ranges of temperature was emphasized. Similarly, observations were also made to determine the characteristic behavior of both larvae and adults in response to these environmental factors. Little has been published on food habits of this insect; thus, emphasis was laid on a study of the effect of diet on sexual development and reproduction. Results obtained have shown that sugar and milk appeared to be two vital nutrients for the adult fly, and that bovine blood could increase sexual maturation and egg production. Considerable attention was also given to the relationship between illumination and sexual development and reproduction. It was found that increased illumination resulted in acceleration of sexual maturation and increased egg production. / Master of Science