A two-year study in the Adirondack Mountains of New York State demonstrated that a groundapplied, larvicide program using Bacillus lhuringiensis var. israelensis (Bli) was a technically feasible method for the area control of black flies. The program required 102 discharge measurements and 480 applications ofcommercial formulations of Bli at dosages equivalent to 10 to 30 ppmfor 1min. Treatments were made to all streams within a 3.2-1an radius of the hamlet of Onchiota between April 1st and July 15th, 1983. The larviciding program was successful, with stream samples(n= 131) indicating a mean larval mortality(\textpm 95\% CI) of97.8\% (96.9-98.5\%). To measure adult activity, 1,008 and 168 one-min, insect net sweeps were made, respectively, in the 32.2 Jan2study area and at a distant control site between May 15th and July 31stboth in 1982 (pretreatment year) and 1983. Analysis of these data (39,766 adults in total) indicated that thelarviciding program resulted in statistically significant seasonal reductions in adul tblack flies: 85.8 percent at the center of the Onchiota community and 58.1 percent at its perimeter, i.e., at 1.6 Ian from the center. Thus, the Bti program achieved an average seasonal reduction of 72.0 percent in the target community. As expected, the largest adult reductions in all three genera, i.e., Prosimulium, Simulium, and Stegopterna, were recorded at the center of the community. These results suggest that in similar habitats adult black fly reductions of ca. 86 percent and 58 percent can be achieved at points 3.2 Ian and 1.6 Ian from untreated areasirrespective of the size of the total larvicided area that a community might decide to establish ..

For communities interested in a Bli - black fly.control program in similar habitats, a first-year base cost of ca. 400/km2 of treated area can be expected. This represents the sum of the preparatory expenses of 70-90/km2\textbulletwhich would be unnecessary in subsequent years, and the actual treatmentexpcnses of$240-380/km2\textbullet which would likely decrease after the initial year due to increased efficiency of operation. Equipment puochases. liability insurance. training, etc .\textbulletwould be in addition to this base cost. Labor would be the primary expense, with the cost of purchasing B Ii formulations less than 5 peocentofthe total budget. Such prices will likely make grourId-appliedcontrol programs with Bli economically feasible in the Adirondack Mountains of New York, since the cost for aerial application of broad spectrum insecticides for adult black fly control is considerably higher.