Abstract: Everywhere in the world and especially in subsaharian Africa, human food is mainly based upon amylaceous crops, mainly Cereals. Unfortunately, the harvest depends of the rainy season length and stored Cereals are attacked and rapidly destroyed by numerous insects. The weevils of the Sitophilus genus are the most dangerous pests of Cereals. Legumes seeds are toxic for these weevils. Traditionally, in Africa and India, mixed legume seeds to cereals permit to prevent them from attacks by Sitophilus weevils. Classical extraction and purification techniques allowed establishing that the toxic compound is a small protein of low molecular weight of 5200 Daltons. The characterization of this protein opens the way towards a new method of protection of the stored cereals.