Collection of blood-engorged black flies (Diptera: Simuliidae) and identification of their source of blood.

Blood-engorged black flies were captured by 2 methods: early morning application of a quick knock down insecticide (resmethrin) into tree canopies, and late afternoon to early evening truck trapping. More engorged flies were captured per man-hour with the tree spraying method than with the truck trap. The percentages of females captured by the spraying and truck trap methods that were engorged were 18 and 1.3, respectively. The most commonly engorged species captured were Prosimulium magnum and P. mixtum/fuscum, and Simulium jenningsi and S. venustum (70% of total). Blood sources of 12 black fly species were identified. Mammals comprised 95% of the blood sources identified. The most common hosts were equines (31%), bovines (25%) and raccoons (19%). Seven percent of all meals identified were from mixed sources, of which 43% involved both mammals and birds.