One of my favorite surprises of summer trout fishing in Minnesota comes after a good soaking rain. When storms sweep through the valleys, they don’t just raise the rivers a few inches. They send ants tumbling from trees and grass into the currents, and the trout are quick to notice.

Ants are an important part of a trout’s diet during the summer months. A sudden flush of these insects drifting along the surface is like a quick meal ticket. In my days investigating the diets of brown trout in Minnesota’s Driftless, stomachs were packed with ants, along with a few other terrestrials including aphids and centipedes, post heavy rain.

As anglers, we can use this to our advantage. Keep a few ant patterns in your fly box once summer rolls around – these are a go-to following a mid-summer rainstorm.

Here are a few tips:

• Look for spots where currents slow down, like seams, eddies, and backwaters, because ants tend to collect there.
• Keep your drift as natural as possible since ants don’t skate across the water.
• Don’t be afraid to try slightly larger ants if the water is stained or flowing higher than usual.
• Try fishing a small sinking or damp pattern as a dropper on a larger terrestrial.

If you like tying your own flies, check out the video above from Fly Fisherman Magazine. It’s easy to tie, rides high, and has fooled plenty of trout for me over the years.