And if you still just can't stand the infestation, know that the swarms should end ... in Lake Erie and they may develop at slightly different rates." While fish flies can be spotted across ...

Though the swarm may appear terrifying, and causes car accidents, it's actually a good sign for the health of the river. The flies are sensitive to pollution and don't survive in dirty water.

Dr Chris Terrell-Nield Dr Chris Terrell-Nield said the "harmless" flies were swarming partly because there ... to the year and unusually warm weather may have sped up their development.