Pyrethrin is a naturally occurring insecticide that is derived from chrysanthemums. It is a potent insecticide that is used to kill a wide range of insects, including flies, mosquitoes, fleas, and ticks. Pyrethrin is often used in pest control products and can be found in pesticides, insect repellents and pet flea shampoos. A few of the synonyms for pyrethrin include chrysanthemum extract, pyrethroid, permethrin, allethrin, and resmethrin. Pyrethrin has become popular due to its low toxicity to humans and other mammals, making it safe to use in many settings. Additionally, pyrethrin is biodegradable, so it does not accumulate in the environment or wildlife.