How Methoprene Works by Julie Froehlig Scientist Methoprene is a chemical that is used to control mosquitoes, without directly killing the mosquito. Many insects go through metamorphosis, similar to the process of a caterpillar becoming a butterfly. Mosquitoes go through a similar process, with a larva turning to an adult mosquito.
Hormones play a similar role in people.
For example, when teenage boys turn into adults, hormones cause their bodies to grow taller and their voices to get deeper. Some scientists had an idea that instead of using pesticides to kill insects, they might just use hormone-like chemicals to stop the natural development of the larva to the adult. Methoprene has a similar shape to a natural insect hormone which controls metamorphosis. So when methoprene is present, it interferes with the natural process and stops metamorphosis from taking place. The larva never turns into an adult mosquito, and the insect cannot reproduce.