U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska
Date of this Version
1998
Citation
EDIS, June, 1998, EENY-030, pp. 1-4
Abstract
Introduction
Florida occasionally experiences outbreaks of black flies, though this is a rare occurance, and these large populations are caused by rainfall extremes. Common names for this pest include black flies and turkey gnats, as well as a number of new names applied by Floridians which are not repeatable here. Because of the hump visible behind their head when viewed in profile, black flies are also called buffalo gnats. Like eye gnats, they fly around people's heads, occasionally getting into eyes and ears as well as crawling in the hair. Because most of the specimens collected to date have been identified as Simulium slossonae Dyar & Shannon, biological information given below will generally be for this species.
Black flies are found in many parts of the US and Canada, including Florida. Populations in Florida normally are not present in numbers large enough to be noticed by humans. Simulium slossonae is found in Florida from Dade country north to Duval county, and west to Escambia county. In some areas it is present all year long. In South Carolina, population peaks have been recorded in late July, late September, and late October, but large numbers have been found in Florida between April and November. Overall, Florida has 18 different black fly species, the most common with populations present from August through July. Only female black flies feed on blood. Males feed mainly on nectar.
Black flies can occur in enormous numbers. Immature stages develop in oxygenated water sources, therefore adults are usually associated with slow moving streams, creeks, or rivers where the immature stages develop. Flowing water does not necessarily imply white water rapids, but water must be moving. Water in lakes and ponds that is not flowing is unsuitable for black fly development. S. slossonae prefers fairly small, slow moving streams with an average velocity of 1.5 ft per second. Water is often tea-colored, with ample vegetation, light shade, and a pH of 4.4 to 4.5. S. slossonae makes good use of temporary streams that flow seasonally.