Grasshopper and Locust Pests in Africa

Africa has an exceedingly rich fauna of Orthoptera, including several families and well over 1,000 species, that could be considered to be grasshoppers or locusts. In Africa (also in Asia, Australia, and South and Central America), some grasshoppers are called “locusts.” This term is applied to species of grasshoppers that display phase polymorphism. Phase polymorphism is largely a behavioral change between different states: gregarious and solitary forms, with intermediate forms called “transiens.” During the gregarious phase, which is induced by high densities, locusts tend to disperse long distances in groups (during the nymphal stage the groups are called bands, during the adult stage they are called swarms). These same species are not very dispersive, nor gregarious, during the solitary phase. Physical changes in appearance may also occur during the change in phase, and of course physiological changes underlie the behavioral and morphological shifts. Transition between the...