The Desert Locust, Schistocerca gregaria (Forsk., 1775), in gregarious phase has long been known for its great polyphagia and broad variety of attacked crops, This polyphagia seems more limited in the solitary phase, Not doing damage in this phase, its feeding regimen is poorly known.

The present work treats qualitative and quantitative evaluation of food preferences of S. gregaria in the solitary state in various biotopes of the Algerian Sahara. The qualitative evaluation was done by comparing the diversity of plant species in the acridid's biotopes with the diversity of the plant species identified in feces of individuals captured on the ground. The quantitative evaluation was done by comparing the frequencies of the plant species observed in feces, with their abundances in the corresponding biotope. The frequency of a consumed plant species then could be estimated by the ratio of the number of imagos having consumed the plant species to the number of imagos present in the biotope. The disparity observed between the frequency of the consumed plant species and their abundances in the biotopes attests to a clear food preference expressed by solitary S. gregaria. The floristic composition of the biotopes influences the food mode by limiting possibilities of choice for the acridid. The feeding regimen differs little according to the sex of the individuals in the same biotope. It appears that the feeding regimen of the Desert Locust depends simultaneously on the composition of the flora and the choices by which it operates in the search for food. The plants appreciated by the Desert Locust are generally those which allow it the best development and the best reproduction.