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The trout fishing on the Bighorn River has been exceptional for the last two to three weeks and it is largely attributable to caddis fly hatches and egg laying by two or three species of caddis. I thought I would write some brief observations of the caddis and call it good.

I decided to check on a couple of the scientific names of the caddis, boy what a mistake that was! Since there are more than 12,000 species of caddis, it really was mind-boggling. Yes, there were sites on the Internet that helped me narrow things down a bit, but not where I was comfortable with naming critters.

Suffice it to say that the caddis flies that I have seen on the river go by the common names of tan caddis, black caddis and, sometimes, sedge caddis. The black caddis hatch is probably the most recognized on the Bighorn River. I have noticed black caddis hatches from the first year I guided on the Horn, 1985, through this year.

Black caddis is probably a member of the genus Brachycentrus, a tube-case-building larva. The black caddis hatch on the Bighorn River is usually one of the most prodigious ones of the entire year, only exceeded by some of the midge hatches.

While trout feed on the emerging black caddis as they swim up, the most feeding activity in my estimation occurs during egg laying. Female black caddis do not have enough power in their ovipositors to break the water surface film so they must land on an object protruding from the water, crawl down it, lay their eggs and release and float back up to the surface. It is when the black caddis are floating back to the surface or floating on the water surface as spent caddis that the trout really concentrate on them.

It took me 10 to 15 years to figure out that black caddis would land on a fallen tree, a rock or a bridge abutment and enter the water on those objects. I used to have several downed trees that I would check out about one-and-a-half hours before dark. Most often there would be 10 to 30 trout lined up on the current lines that came off each tree. I found out that a black CDC caddis trailing a black caddis emerger worked very well when fishing during the egg-laying time on the river. If I had an accurate fly fisher, he or she could pick off three or four trout out of each current line before the rest spooked. In short, I could spend a whole evening at one spot.

While most of my downed trees were washed away last year, there are still areas in the Bighorn River that attract egg-laying black caddis.

What has made for spectacular daylong fishing on the Bighorn River has been the tan or sedge caddis (Hydropsyche) hatch, egg-laying activity and cripples. This caddis has been unusually common this year and has made for some explosive fishing.

The caddis is pretty decent-sized, at least a 16 if not a 14 hook size. The caddis swims up rather aggressively and is soon airborne. The trout chase the emergers and often end up breaking the surface, which some anglers misinterpret as a rise. The tan or sedge caddis sometimes doesn’t make it through the surface film adequately and ends up being a cripple — one critter that the trout pick off with gusto.

If the tan or sedge caddis is able to fly off, they end up mating and the females come back to the water in the afternoon to lay their eggs. This species has enough power to break the surface film and extrude eggs which are denser than water and settle to the bottom.

The trout have been zeroing in on the egg layers. The rise could be described as a toilet flush and it wouldn’t be much of an exaggeration. Sometimes the female caddis becomes ensnared in the surface film and flutters across the water. She usually has about a 30 second lifespan when that happens.

Many anglers have been fishing tan elk hair caddis in sizes 16 or 14 throughout the day with great success. The demand for that pattern has been so great that the fly shops have run out of them.

By the by, if you don’t have luck fishing tan caddis patterns dead drift, don’t be afraid to twitch them and give them a little life. You will be surprised at the explosive strikes evoked by movement of a dry caddis fly.

Well, I am heading out to fish the hatch. Have a good time fishing or hunting this weekend!

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