Demon WP Insecticide, with cypermethrin 40.0% kills large roaches, spiders, crickets and more. It can be used inside or outside. Demon WP Insecticide in its envelopes has been a number one seller for many years due to it's convenience of use. Simply drop the packets in the envelope in water (they dissolve). Demon WP Insecticide works well for a variety of insects, lasting up to 3 months. A gallon of finished of Demon WP mix usually completely covers a 2,000 to 2,500 sq. foot home.