Neem trees are native to India and Burma and are a botanical relative of mahogany. The main active ingredient of neem oil is Azadirachtin. Neem has been used for centuries in India for pest control.
Neem oil is biodegradable.
Neem has many main modes of action with the primary role of disrupting an insect's metamorphosis. It is most effective on younger stages of an insects development than when they have reached their adult form. Best control is achieved when insect populations are light to moderate. Neem makes an excellent antifeedant and repellant when sprayed on plant foliage. It has an extremely bitter flavor to it which can make many insects stop feeding on the host plant.