a naturally occurring substance that belongs to an organic molecule class called tetranortriterpenoids ... It is structurally similar to insect hormones called "ecdysones," which control the process of metamorphosis as the insects pass from larva to pupa to adult. Metamorphosis requires the careful synchrony of many hormones and other physiological changes to be successful, and azadirachtin seems to be an "ecdysone blocker." It blocks the insect's production and release of these vital hormones. Insects then will not molt, thus breaking their life cycle. Azadirachtin may also serve as a feeding deterrent for some insects ...