The state of Rondônia in west central Brazil apparently has the highest reported butterfly diversity in the world, with an estimated 1,500-1,600 species living within several square kilometers in the central part of that state. A preliminary checklist of over 800 identified species is given, and some of the factors contributing to this diversity are described. The tropical rain forest in this area is being rapidly cleared for development and the creation of one or more inviolate biological preserves is urgently needed in order to save a living sample of the incredibly diverse fauna and flora for study by future generations.
