Paul Shaffner, Matema lake flies via Flickr.

Look closely at the picture. It’s taken in Matema in east Africa. Do you see the black fuzzy haze just above the horizon?

Here’s another one:

https://www.flickr.com/photos/martijnmunneke/

And another:

Martin Grimm https://www.flickr.com/photos/mgrimm82/ Used with permission

That’s not smoke. Those are flies.

These lake flies depend on water for reproduction. After the larvae living in the lake have pupated, the pupae float to the surface, where the flies emerge by the millions.

The locals love when the flies emerge. According to The Insect Cookbook, people collect them in large, flat baskets. They moisten the baskets and wave them around in the swarm, which causes the flies to get caked onto the basket surface. They’re then emptied into boiling water, drained, and dried in the sun. The resulting fly cakes are considered a delicacy, and are almost 70% protein. (p. 31)