Haemagogus species

Haemagogus mosquitoes are the primary vectors of sylvatic (jungle) yellow fever in Central and South America. Unlike the urban Aedes aegypti cycle, the Haemagogus cycle maintains yellow fever virus in forest monkeys — with humans as occasional incidental hosts who venture into the forest canopy.

The mosquito itself is striking: a metallic blue-green sheen on the thorax and abdomen that is noticeably iridescent in sunlight. It is a forest-canopy specialist, descending to ground level mainly in humid conditions, and bites exclusively during daylight hours.

For travellers, the practical risk is from entering unvaccinated into South American rainforest regions. Urban yellow fever outbreaks can spill from sylvatic cycles when unvaccinated humans carry the virus back to cities populated by Aedes aegypti.