Population profile of stable flies (Diptera: Muscidae) caught on Alsynite traps in various feedlot habitats

Cylindrical traps made from Alsynite fiberglass were placed in 4 habitats in a confined cattle feedlot environment from 2 May to 30 October 1996 to evaluate abundance, sex ratio, physiological age structure, and blood-fed status of trapped adult stable flies, Stomoxys calcitrans (L.). Significantly more stable flies were caught on the trap located between host cattle and trees. The abundance of stable flies decreased geometrically with increasing distance from the host cattle in the open area. The spatial distribution of adult flies in cattle feedlot habitats became less heterogeneous as the population density increased. Male stable flies clearly dominated the total collection (66.7:33.3, male:female). A higher proportion (38.9%) of female stable flies was found on the trap close to a major immature developing area (manure pile). Most of the trapped flies (64.8%) showed a positive blood-fed status, but only 331 (8.8%) of 3,767 flies had recently fed. A majority (72.6%) of the attracted females was at the early nulliparous stage. Trap positioning did not have any significant influence on specific physiological age groups of the captured flies