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. Neem oil works by suffocating insects or disrupting how they feed. The pest must be present when the oil is sprayed on the plant to be effective. When applying neem oil, cover all parts of the plant. Make sure to spray the undersides of leaves where pests can hide and lay eggs.