In conjunction with my recent posts on Brazilian bugs, here’s the Borrachudo (aka Black Fly in English).
A black fly (sometimes also called pium in Brazil) is an annoying little bug, much like the mosquito, although more silent. There are over 40-50 known species of black flies in Brazil. The majority of species belong to the immense genus Simulium. Like mosquitoes, to which they are related, most black flies gain nourishment by sucking the blood of other animals, although the males feed mainly on nectar. They are usually small, black or gray, with short legs and antennae. They are a common nuisance for humans, and many U.S. states have programs to suppress the black fly population. They are able to spread several diseases, including river blindness in Africa and the Americas.
They generally fly close to the ground, therefore biting your ankles or hands, assuming they are at your side. The bite mark is bigger than that of a mosquito and in my experience, usually only itches (and it itches a lot) days after instead of the moment after they bite. For this reason, its hard to notice them when they do bite. In Brazil, they stick to wetter areas such as forested regions and especially near waterfalls.