Neem oil contains many ingredients that are extremely beneficial to the skin. Some of those ingredients include: fatty acids (EFA) limonoids. It reduces insect feeding and acts as a repellent. It also interferes with insect hormone systems, making it harder for insects to grow and lay eggs. Azadirachtin can also repel and reduce the feeding of nematodes. Other components of neem oil kill insects by hindering their ability to feed.