Wisconsin Is Getting Smothered by Millions of Gross, Horny Flies

When people monitor the weather radar, they often have to make judgment calls about whether to head inside. But anybody who saw what exploded on the Doppler Sunday evening over La Crosse, Wisconsin, better have skedaddled for shelter—or be covered by thousands upon thousands of tiny, horny flies:

This storm-cloud-looking apparition is actually a massive swarm of mayflies, an "emergence" of them, to get all Lovecraftian. Mayfly nymphs spend a year or two in the water (in this case, the Mississippi River) munching on organic decay. Then, when summer arrives, they take flight en masse and proceed to make sweet bug love before immediately going back to the water to lay eggs and die.