Black flies are like giant, mutated mosquitoes in a way, and are a major problem in northeastern states and on the U.S./Canada border. These large flies are blood suckers and can ruin populations near waterways, where black fly larvae grow up. Through a number of different techniques, black fly populations can be controlled, and personal protection against the flies can be put into play.
Set up a temporary dam two weeks prior to black fly season in any stream with running water. Black flies lay their eggs in streams and the larvae require moving water to gather nutrients. By damming the waterways with sand bags, stagnant water is created that will keep black fly larvae from maturing.
Clean up any debris that may be found in the waterways. This will remove places where black fly larvae can attach themselves to grow.
Set BTI cakes in the water after it is dammed. These will kill off black fly larvae, as well as other pests such as mosquitoes that grow in watery areas.
Use a type of insect fogger, such as Raid, that is pyrethrin-based. This is a temporary way to get rid of black flies in a small area.
Apply DEET insect repellent when going out where black flies have infested. This will keep most of them from biting you.
Wear a head net when venturing out to areas where black flies are in high numbers. Also wear long sleeves, pants and gloves to cover up as much skin as possible.