Doktor Doom's residual foam injects deeply into cracks and crevices where ants hide, smothering and killing the pests for months. The formula combines pyrethrin for a fast initial kill with permethrin for long-lasting residual control that keeps ants at bay long after the initial treatment. Simply inject the foam around door sills, window frames, utility pipes and garden beds to create an ant-proof barrier that seals out ants for good.