A family of insecticidal polypeptides expressed in the venom gland of spiders of the genera Atrax and Hadronyche have been described. Also included are polynucleotides and expression vectors encoding the polypeptides and insect viruses and cells expressing the polypeptides. Transgenic plants and insects expressing the insecticidal polypeptides are also described. The insecticidal polypeptides may be employed in methods and compositions for treating insects, insect larvae, and plants.