Scorpion flies look similar to lacewings, but they are a separate species. So named because the abdomen of the male is upturned like a scorpion. You can see the difference between the male below and the female in the second picture, his tail does look quite threatening. They also have a characteristic elongated head. They fly around in shady areas, and can be found on foliage such as brambles. These were in the woods at the far end of the river.