It kills insects by hyperexcitation of the insect nervous system. It occasionally eats invertebrates such as insect larvae. Predatory leeches feed on small invertebrates such as snails, earthworms and insect larvae. The protein is poisonous to certain insect pests. The resulting GMOs are resistant to some insect pests. Aphids are eaten by many bird and insect predators. "Ribes" plants are susceptible to several diseases and a number of insect pests. It has been used as a natural insect or pest deterrent. This acts as a natural insect repellent. It functions to attract insect or bird pollinators. This applies particularly to some insect and mite plant galls. The wood is resistant to insect and fungal attack. Tetrachromacy is demonstrated among several species of bird, fish, amphibian, reptile, insect and some mammals. They are susceptible to heavy damage from rains, winds, and insect infestation. Entomologists also compared grazing lambs to insecticides for insect control in winter alfalfa.