Abstract:Numerous mushrooms are toxic to insects. To identify the chemicals involved in insecticidal activity, the toxicity of 14 species has been studied for water solubility, thermolability, and dialysis. The data strongly suggest that proteins are responsible for most of the insecticidal avtivity in mushroom fruitboodies and may be a source of genes available for plant protection against insects. Among proteins, lectins and haemolysins are good insecticide candidates because the toxicities are not affected by protease.