A friend and I were driving along Lake Mille Lacs on Thursday evening when we heard what sounded like rain hitting our truck.

But it wasn't rain, it was clouds of midges that had recently emerged from the lake. So we pulled into a public access to experience the amazing annual phenomenon.

And it was amazing. We almost needed head nets to breathe. At the time, I mistakenly thought the bugs were mayflies, but Rick Bruesewitz, DNR area fisheries manager, said they were midges – commonly called fish flies or lake flies – a smaller variation of the flying bugs.

Black clouds of them hung over the highway and the lake, and, of course, quickly covered us. The billions of bugs produced a loud, eerie hum.

"It is an incredible thing,'' said Brusewitz. "It happens just about every year. They (clouds of bugs) look like tornadoes. You'll have spirals of them above trees or roads. Some nights are worse than others.''

Like mayflies, the midges emerge from their larval stage at the bottom of lakes, then float to the surface and eventually fly away. Fish gobble them up in the water, and birds do likewise once the bugs are airborne.