Acephate is an organophosphate foliar insecticide of moderate persistence with residual systemic activity of about 10–15 days at the recommended use rate. It is used primarily for control of aphids, including resistant species, in vegetables and in horticulture. It also controls leaf miners, caterpillars, sawflies and thrips in the previously stated crops as well as turf, and forestry. By direct application to mounds, it is effective in destroying imported fire ants. Acephate is sold as a soluble powder, as emulsifiable concentrates, as pressurized aerosol, and in tree injection systems and granular formulations. It is considered non-phytotoxic on many crop plants. Acephate and its primary metabolite, methamidophos, are toxic to Heliothis spp. that are considered resistant to other organophosphate insecticides. Acephate emits toxic fumes of phosphorus, nitrogen, and sulfur oxides when heated to decomposition.