Simulium

The bilharzia snail and the Simulium fly (host to an organism causing blindness), the tsetse fly, and the mosquito collectively affect human beings and their livestock far more than do such individually large or formidable species as lions or elephants.

…by flies of the genus Simulium. These flies breed along fast-moving streams. The condition is widespread in southern Mexico and Guatemala and is common in central Africa. Characteristic lesions are nodules beneath the skin, usually in the head region; the infection may also invade the eyes, causing blindness in about…

…black flies in the genus Simulium. The disease is found chiefly in Brazil and Venezuela in the Americas and in sub-Saharan Africa, in a broad belt extending from Senegal on the west coast to Ethiopia on the east; in Africa its northern edge is about 15° N of the Equator,…