Study of aphid saliva: a prerequisite to new bio-insecticides development. Aphids, major insect pests of forests, cereal, vegetable, fruit and ornamental crops, are controlled mainly by synthetic insecticides. However, due to the adverse effects of these ones on the environment and the development of resistant populations of aphids, it is essential to adopt alternative control. Aphid saliva plays a key role during insect feeding. It contains a wide variety of compounds whose specificity of action allows to dissect some physiological mechanisms that govern the interactions between the insect and its host. Some identified compounds were found to induce defences of their host and are therefore considered promising tools in the fight against insect pests. One of the possible strategies is based on research and recovery of substances found in aphid saliva. This approach has been developed especially in hematophagous insects such as mosquitoes. The current state of knowledge about aphid saliva is discussed in this article in parallel with saliva of chewing phytophagous and hematophagous insects.