The Salmonfly Hatch

June 1, 2012

The Salmonfly Hatch

By Dave Kumlien
Outfitter for Montana Troutfitters

It's June. And that's \"Big Bug\" time in Montana!

The salmonfly, the largest member of the stonefly family of aquatic insects, will soon begin hatching on Southwest Montana's rivers and streams.

The attraction of the salmonfly is that the physical size and trout food value of this insect (adult females are nearly 3 inches long) dwarfs all other aquatic insects. They will move even the largest trout in the river to feed on the surface. No other hatch provides this opportunity!

As the water warms and days lengthen, the larval form (nymph) of the salmonfly begins to migrate toward the banks of the river. When conditions are right, the nymphs crawl out of the water, grasp vegetation along the bank (like willows), split the nymphal case, and the adult fly emerges. The two sets of wings unfold and dry, and over the next few days the adults mate and fly out over the river to lay eggs.

If you sat down to create the perfect trout lure, you couldn't do a better job than Mother Nature has done with the salmonfly. First, the insect is large and clumsy, and very often falls from its perch in the bushes along the bank or crash lands on the river surface when returning from a flight.

Once on the surface, the salmonfly twitches six legs and flaps four wings in a frantic effort to return to the safety of dry ground. This action is irresistible to the trout, and the typical salmonfly strike proves this. There's no guessing about the take. It looks a little like somebody threw a bowling ball on your fly. Breathtaking!

The progression of the salmonfly hatches in the Bozeman area generally starts with the Beartrap Canyon on the Madison River and the lower Big Hole. The hatches move upstream with increasing water temperature.

While not absolutely predictable, emergence of the nymphs will often cover 5-7 miles per day. Once the adult is out in a given stretch of river, it will take another 4-6 days to finish the mating and egg laying cycle.

On an average year, following the Beartrap, the big bugs will show up on the Upper Madison around Ennis about June 22-25, on the Gallatin about July 1, and on the Yellowstone at the same time. If you are gainfully unemployed, retired, or irresponsible, you can fish salmonfly hatches from Memorial weekend through the middle of July! These dates of course vary from year to year as Mother Nature follows no calendar.

Montana Troutfitters is your salmonfly hatch headquarters with the best collection of salmonfly adult and nymph patterns in the area and most important, the latest and most accurate information. We make a real effort to keep track of water and hatch conditions and keep our fishing reports up to date. If you want to stay on top of the hatch sign up for our Newsletter Today!

Enter your number below to receive new, up-to-date river reports from Montana Troutfitters.