Liberty 50 Plus IGR Spot-On for Dogs by Star Horse kill fleas, ticks, mosquitoes, lice and mites. Our products feature active Permethrin that is known to be one of the safest pest control products on the market - in fact if you check any of the Spot-On Websites, you will not find Star Horses products listed as having any negative reactions.Do not use on cats. Kills, Repels and Prevents Re-infestations of: Fleas for up to 5 weeks. Ticks for up to 6 weeks. Mites & Mosquitoes for up to 4 weeks.