gnats

[oldmangrinn]

why do gnats always fly in a "cloud" about head height above a path ,especially in woods?

[CatInTheHat]

Oldmangrinn, as far as I know, those clouds aren't the gnats which bite you mercilessly. They are males collecting on the lookout for (more solitary) females to pass by, in the hope of finding a mate. Females need a 'blood meal' from a mammal before they can lay their eggs, and it is they which bite you. The males congregate where they do because it's the optimum spot for finding a mate. After mating the female then finds you (or another warm-blooded mammal), has her blood meal and can lay eggs. There are various thoughts on what attracts the females to their nosh - pheromones from the skin and chemicals from breath among them.