The Neem (Azadirachta indica A. Juss.) http://www.greeneem.com/ has been known as the wonder tree for centuries in the Indian subcontinent.

Neem comprises of 40 different active compounds called Tetranortriperpernoids, or more specifically liminoids. These liminoids create hormonal disruptions and prevents the insect from Feeding, Breeding or Metamorphosing.