Giant Mosquito (?) in Northern Minnesota

Or crane flies?

always reminds me of crane flies, but the description of the activity sounds just like the mating swarms of giant Hexagenia mayflies that are often seen on many MN lakes at this time of year.

EDIT: A Lake Vermilion fishing report for Aug. 17 mentions "a greasy black fishfly" emergence occurring on the west end of the lake. "Fishfly" is a common name for Hexagenia mayflies, and the "greasy black" description might be referring to H. atrocaudata.

I looked at some photos of crane flies and I'm pretty sure that's what these were. I know there was a large emergence of mayflies on Lake Vermillion this year, but these insects did not look like mayflies. Crane fly wings and mosquito wings must make a similar noise.

From OSU Extension: "Most occur in huge swarms or in compact mating swarms, and a "humming" can be heard over a considerable distance."

I live in the general area, and certain mayfly gatherings HAVE been enormous. BUT, I wonder if something else would be causing the buzzing noise. About when the poster had made his post, the Linden/Basswood trees were blooming. The hum of bees and other pollinating insects can be quite loud. I could be wrong though.

I've never seen swarms on my lake large enough to cause such a ruckus, but who knows! This was quite a year for big bug numbers.

It's hard to say whether other insect noises might have contributed to the loud buzzing, but a large enough number of the giant mayflies might be sufficient to account for it.

We don't usually associate mayflies with noises, but the sounds made by very large Hexagenia swarms can be quite loud. Although stream populations of Hexagenia seldom come anywhere close to the scale of those occurring in the largest lakes or rivers like the Mississippi, notice how Justin Leonard describes a smaller stream event:

"Then transforming to the spinner stage, they form a mating flight which constitutes one of the most spectacular phenomena of insect behavior in the north-eastern United States. Enormous swarms form at or above tree-top height and they follow the course of the stream for miles. The rustle of wings is clearly audible at some distance from the swarm."

I think it is probably a matter of scale. At some times and in some places, Hexagenia emergences are modest events; at other times and in other places, snowplows have been called into service in order to clear the streets of massive accumulations of dead or dying Hexagenia imagos.