R.I.P. Fleas Extra Household Spray RIP Fleas contains: Tetramethrin: a second generation synthetic pyrethroid and a contact insecticide with a rapid knockdown action of insect pests. It interferes with the nerve impulse transmission by acting upon the sodium channels in insects providing rapid paralysis preventing fleas from biting potential hosts. Permethrin: a potent insecticide with powerful contact action, it is light stable and was the first synthetic pyrethroid authorised by the World Health Organisation for household use. It has a lethal effect on insects but due to it’s chemical structure it has a low toxicity to most mammals and is ideal for the control and prevention of insect infestations. Methoprene: a compound that mimics the insect juvenile hormone and arrests development of fleas and house dust mites in the environment; it is a well-proven Insect Growth Regulator. In real house studies methoprene has been shown to be a safe and effective way to control flea development for 12 months. Methoprene has the advantage of being highly fluid at room temperature, allowing it to spread evenly and deeply into the carpet pile.