Black flies
Black flies, family Simuliidae, order Diptera
About
Black fly larvae are filter feeders in stream habitats. They feed on small animals (protozoa and crustaceans) or plants (algae) by using mouth brushes to collect particulate matter from flowing water. Larvae and pupae are usually found on rocks in shallow water.
Black fly larvae grow up to ¼” in length. They are shaped like a bowling pin, with an enlarged abdomen that has a row of hooks that they insert into a silk pad they secrete. This allows black flies to secure themselves in turbulent and fast-moving water.
Black fly larvae are tolerant of water quality impairment.
Life Cycle
The larval stage can last anywhere from 10 days to 10 weeks, depending on the species. Some species spend winter in the larval stage. The last instar of the larval stage spins a cocoon in which the larva pupates. Black fly larvae pupate under water. The cocoons vary in shape depending on the particular species of black fly. The pupae have branched respiratory filaments that take up dissolved oxygen from the water. These filaments function both in and out of water (this allows the pupae to survive fluctuations in water levels). Depending on the species and the temperature, pupae emerge after a period of a few days to a few weeks as a flying adult.
Reproduction
Adult black flies mate soon after emerging from the water. They mate in flight. After mating, the female finds a source of blood, which is used to nourish the eggs. Female black flies lay their eggs (between 150-500) in running water. They are deposited either singly or in a mass. The eggs hatch within a month of being deposited.
References
- insects.tamu.edu/fieldguide/cimg222.html
- www.depweb.state.pa.us/blackfly/cwp/view.asp?a=3&Q=505606
- http://www.troutnut.com/hatch/884/True-Fly-Simuliidae-Black-Flies
For more black fly pictures, click here
Research conducted by StreamWatch volunteer Ralph Hall