Distribution and habitat
Scanning electron microscope image of the head of Simulium damnosum, showing the compound eye (x 130). The fly is a vector of a parasite which causes river blindness. Coloured artificially by computer. © Natural History Museum, London
Simulium yahense is found in the rain forests of west Africa.
Females lay their eggs in small forest streams where the larvae filter nutrition, such as algae and bacteria, out of the water, taking about a week to grow.
They pupate under water and when the adults emerge after a few days, females fly off looking for a blood meal to supply the nutrition to enable her to develop her eggs.
The Bioko form of Simulium yahense was unique to the island of Bioko, where it transmits river blindness and breeds in such large numbers that it can cause up to 1,000 bites per day, stopping people from being able to work in their fields.
