Black flies (Simuliidae), also known as buffalo gnats because of their humpbacked appearance, are a major pest and often confused with mosquitoes. Accurate identification of black flies can help us make better control decisions resulting in reduced pesticides applications, reduced harm to non-target species, and protecting human health by targeting control efforts at the insects actually causing the nuisance or disease threat.

Large stream black fly habitat in Piedmont Physiographic province. Photo Credit: Dr. Diana Carle

Small stream high elevation black fly habitat. Photo Credit: Dr. Diana Carle

Black fly larvae live predominantly within the riffle habitats of streams where there is an abundance of food particles for the larvae to feed upon. Photo Credit: Dr. Diana Carle

Unlike mosquitoes, black fly larvae live exclusively in running water habitats like streams and rivers because their primary mode of feeding is filtering. Black fly larvae attach themselves via silk pads they create on submerged substrates in riffle and run habitats of a river for optimal food particle gathering. Black flies are an important part of an aquatic ecosystem as they eat and clean up small debris flowing through a stream and also serve as a food source for many predators. In early spring for example, members of the predatory Trichoptera family Rhyacophilidae have been found living within and eating the sticky mass created by hundreds of interconnected black fly pupae of the genus Prosimulium. However, Black flies vector the causative agent of river blindness to humans in Africa, and Central and South America, and are a major nuisance as well as vector of animal diseases in the USA.

The black fly fauna of NJ is quite diverse and includes 39 recorded species; a species list and species descriptions are included in The Black Flies (Diptera: Simuliidae) of NJ (Carle 2010a). Control of these flies is targeted at the larval stage before the immatures emerge into adults and leave their lotic habitats The pesticide used is derived from a naturally occurring soil bacterium, Bti. Because only certain species of black flies vector disease or even a nuisance, proper surveillance and identification of the species present is necessary before making any control decisions.  Also unlike mosquitoes, species identification of both larval and pupal black flies is possible. For black fly identification tools see, Identification Keys to the Black Fly Larvae and Pupae of NJ (Carle 2010b).