My main objective is to investigate the behavior and morphology of migratory locusts in both solitary and gregarious phases, particularly focusing on the stimuli and chemical agents inducing these phase changes. Early on, these two phases were recognized as two distinct species. However, a Russian-British entomologist Boris Uvarov later discovered these forms are density-dependent phases of the same species. It means that solitary ones are less social under low population density, while gregarious ones are more social under the conditions of increased population density.