Pines and gnats

Standing on a promontory above a line of pines facing west in late afternoon, I could see a small cloud of gnats above each tree, like a flame above a candle. The temperatures were warmer than normal for the season, but still cool.

The Wikipedia article on Gnat states:

Male gnats often assemble in large mating swarms, or ghosts, particularly at dusk.... The mating occurs as soon as the females enter the swarm.

Perhaps there was plenty of water nearby, or wet rotting matter near the trees. Or perhaps the females are more likely to show up there, above the pines.