Pyrethrins-based PurgeĀ® III insecticide is metered insecticide formulation for flying insect control. It kills insects such as flies, mosquitoes, gnats and small moths for a full 30 days. Purge III leaves no lingering insecticide odor. For the most economically-effective flying insect control, trust Purge III, formulated with 0.975% Pyrethrins.