A new plague of the Desert Locust Schistocerca gregaria started in 1986; it developed quickly in 1987 in the Sahelian countries and reached northwest Africa at the end of 1987. It expanded in 1988 in north Africa, the Sahel, the Sudan, the Near East, southwest Asia, and in october 1988, swarms crossed the Atlantic to the Caribbean. The plague declined dramatically in the past quarter of 1988, and by March 1989 the plague was over. A study of the latest known upsurges provides more support to the theory that a build-up of locusts arises from initially low-density populations rather than from the persistence of undetected swarming populations. The decline of the recent plague was probably attributable to the cumulative effect of control operations combined with natural environmental factors. Prevention of new plagues of the Desert Locust will be much more difficult as the restriction on the use of dieldrin poses major technical, logistic and financial problems.