Funding comes from a combination of state legislature appropriations and participating counties. In 1997, it is anticipated that 42 streams and rivers in 28 counties will be enrolled in the program. DEP monitors selected stream areas for the presence of black fly populations. Stream flow conditions, water temperatures and larval counts determine when and where spraying occurs. The purpose of spraying is to kill larvae of the black flies before they emerge into adults.
Monitoring also occurs after spraying to determine the effectiveness of the treatment.
DEP monitors adult black fly populations using a collection net which takes sweeps at designated collection sites to determine the effectiveness of the program within participating counties. The spray material is commonly called Bti. Bacillus thuringiensis var. Bti offers a safe and effective alternative to chemicals to kill black flies with no harmful effects to other aquatic insects and fish. Only the black fly larvae, not the eggs, pupae or adults, feed on Bti particles in the water, resulting in larval mortality.