Once mosquito season has started, use two boxes per acre. The mosquito population will suffer dramatically within about the first 15 days and will be up to 95% controlled for up to 90 days. The Spartan Mosquito Eradicator is a uniquely effective, long-lasting, continuous mosquito control system. Doesn’t require batteries or electricity; just add warm water, shake, and hang according to the directions! The special formula and specially designed delivery system attracts and eradicates mosquitoes and lasts up to 90 days. MAINTENANCE Water evaporating will not harm the effectiveness of the product so long as water levels are maintained between the fill and low level lines on the label. Placing product in shade according to directions will reduce water evaporation. Product will last up to 90 days and should be replaced at least every 90 days during mosquito season.