The Importance of Midges on the Big Horn River

The Importance of Midges on the Big Horn River

January 31, 2012 8:50 pm Published by Leave your thoughts

Midge Matters on the Big Horn River

by Bighorn River Fly Fishing Guide David Palmer

A Stomach Pump Full of Midges

In Gary LaFontaine’s book, “Fly Fishing the Mountain Lakes”, he states that a gram of scuds is 3880 calories while a gram of midges is worth 5280 calories. Given that there are quite possibly billions of midges in a relatively short stretch of the Bighorn River, you can see why midges matter.

Midges live an all types of water but are especially abundant (and important) in tail waters like the Bighorn.

Midges are a mainstay meal for trout on the Bighorn throughout the year, especially during the winter when other insects aren’t available.  Midges become a supplemental meal during the summer and fall when other food sources become more readily available.

Winter and spring are probably the best time for anglers to take advantage of great fishing on the Bighorn River with midge imitations. Larva, pupa and adults are around every day and as the days get nicer in early spring, the hatches become thicker.

Dry fly midges in the winter, you say? Why yes. Just last February, a friend and I cast midge imitations to dozens of rising fish with the air temperature being a brisk ten degrees. All it took was a little bit of sunshine to get the midges, and subsequently the fish, active.

Midge larva are found in many colors. Olive, brown, tan, red and cream are all common on the Bighorn River. The colors vary with the season and water type. Most midge larva that I find are olive, tan, cream, and red. The sizes are typically small, from size 18 down to a miniscule 28, but occasionally one comes across some that are as big as a size 14. Larva like to live in the river bottom and under rocks, but are in the drift often enough I find them in most stomach samples.

Pupa, the next step in a midge’s life, are as diverse as the larva. Black, olive, tan and root beer are common colors on the Bighorn and vary in size from 16 to 22, with 18s and 20s being the most commonly fished. The pupa are often highly segmented whereas the larva are typically more uniform in color.

As the pupa emerges into the adult, this is where it really gets interesting. Fish can key in on the rising pupa because they are easy (and very abundant) meals. The pupa can get trapped just under the surface film, which can really create a consistent food supply for fish.

Bighorn River Midge Larva

Trout Often Key in on Red Larva

Fish keying in on pupa in the surface film can be quite frustrating especially when the angler can see their tail and dorsal fin breaking the surface. The urge is to put on a dry fly but fish focused on pupa pay little attention to surface flies. A short dropper off a dry can be very effective as well as a very light nymph rig. Swinging emerging style nymphs down and across to these fish can be very effective also.

Adult midges are similar to the larva and pupa in that they come in two sizes, small and smaller. Size 18-20 patterns are effective, but in the spring, there are midges that get as big as size 16.

Once you see noses breaking the surface, the fish are usually willing to look at surface flies. The more common adult midges come in variations of olive, grey, cream, and dark grey (nearly black).

Flies that imitate emergers and cripples, with some part of the fly being below the surface are very effective during the hatch. A long, light leader is essential so small flies aren’t floating unnaturally. The smallest of drag by your leader or fly can result in repeated refusals. Flawless drag free drifts by the angler are the key to success.

The real fun begins when the mating clusters begin to build on the water. Some days, the surface looks like gray fuzz. This mass of mating midges really brings the fish up and they can be pretty indiscriminate since they are just sucking in mouthfuls of midges every time. Perfect presentation isn’t as important because so many midges are skittering on the surface and skating a fly a little bit can grab the attention of a greedy fish.

Griffiths gnats and Adams in size 16 and 18 are very effective when fish are gorging on the mating midges. Just something that mimics a lot of midges dancing close together.

The midge hatch usually presents the angler with two hatches each day, one around mid-day and another in late afternoon. Early, warm days can get midges going as early as 10 am, sometimes earlier but more likely closer to lunch time. The second hatch generally gets going between three and four pm and can last into darkness, but in late winter and early spring, that’s not very late.

While late winter and early spring don’t seem like ideal fishing times (and sometimes they aren’t), the fishing on the Bighorn River, thanks to midges, can be outstanding whether fishing with nymphs or dry flies.  That’s why Midges Matter!

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This post was written by Bighornangler

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