Several areas of the bionomics of Culicoides in Virginia were given preliminary investigation. These included surveys for larval habitats, colonization attempts with Culicoides guttipennis (Coq.), host preference studies and adult activity studies. Breeding sites of 22 species of Culicoides were located and briefly described. Samples of mud, debris, etc. from suspected breeding sites were brought into the laboratory and maintained at 70°F in food containers with screened tops. Most species were found to prefer a specific type of habitat (i. e. tree-holes, polluted areas, etc.) but exceptions were occasionally observed. Colonization attempts with C. guttipennis have resulted in the successful establishment of this species in the laboratory. The colony has been maintained for 12-15 generations and is currently producing over 1,000 adults per day and an excess of eggs. Techniques developed for larval and adult maintenance have proved to be highly successful in recent months. Adults were held in a constant temperature cabinet at 80°F ± 2° and 85% relative humidity ± 10% in semi-darkness (less than 1 ft-c ). Eggs were collected on moist filter paper exposed in shell vials. Fly eggs hatched in 3 days and the young larvae were introduced into aquaria containing leaf mold from hardwood forests and distilled water. Larvae pupated in about 12 days and adults emerged about 3 days later. The adult diet consisted of rabbit blood, raisins, sugar cubes, honey water and a 6:6:1:13 mixture of powdered milk, sugar, egg solids and water administered in capillary tubes. In host preference studies 15 species of Culicoides were collected on 1 or more of 14 different hosts used in animal-baited traps. Animals were restrained and exposed on a small platform. After 15 min the animals were covered with a collecting cage. Flies were aspirated from the traps and killed in 70% ethanol. Even though some preferences possibly were shown by some species, more data will be needed before definite conclusions can be drawn. In adult activity studies, most species appeared to be more abundant from 9 PM to 3 AM as indicated by light traps. This was especially noted in C. stellifer, C. haematopotus and C. venustus. The activity of C. haematopotus was fairly constant up to 3 AM and then decreased. C. stellifer and C. venustus activity decreased as the night progressed. / Doctor of Philosophy