R.I.P. Fleas Extra contains two pyrethroid insecticides (permethrin and tetramethrin), and an insect growth regulator (S-methoprene). These ingredients are known to be effective against the majority of insects and arachnids, but Dechra have no data to support the efficacy of R.I.P. Fleas Extra against any species other than fleas, dust mites and ticks.