In 1994, the effects of fipronil, a new insecticide compound of the phenyl-pyrazol chemical group, was tested against desert locusts during a field experiment in Mauritania. The impacts of these spray treatments on nontarget Coleoptera and Hymenoptera were also studied. In relation to organophosphorous insecticides usually used against grasshoppers and locusts, fipronil appeared more effective and persistent. Similar results were obtained for nontarget Carabidae and Tenebrionidie which were almost totally eliminated from the treated plot. The effects on Hymenoptera varied according the family; Scelionidae and Sphecidae seemed to be more affected than Apoidea. Positive and negative aspects of fipronil treatments are discussed. Appearing as one of the most convenient insecticides to successfully present locust outbreaks, at a very early stage of invasion under Saharan conditions, fipronil simultaneously induces heavy mortality in some nontarget insect groups.