Efficacy of Bacillus thuringiensis (H-14) for larval Aedes mosquito control in intermountain meadows in Wyoming

One square meter field enclosures made of steel flashing, and natural ponds were used to determine the efficacy of Bactimos formulations of Bacillus thuringiensis (H-14) for control of late instar Aedes dorsalis, Ae. fitchii and Ae. melanimon mosquito larvae in intermountain meadows. Low temperatures caused decreased efficacy of the formulations tested in the laboratory, and spring temperature extremes lowered efficacy in field tests. Adequate control of fourth instar larvae was obtained in field studies in a 24 hour period when water temperatures were greater than or equal to 12 degrees C at a treatment rate of 0.1 mg/liter.