Hatch Guide: Mother’s Day Caddis

Note: Not sure when I wrote this or for whom, but I found it while searching my files and thought it would be worth posting. You’ve got a couple months before this hatch hits, but it’s worth thinking about it now and getting those flies in order, or tying some to supplement what you may have lost last year.  GT

The mother’s day caddis is a hatch I love to hate.

Half the time it comes off when water conditions are sketchy at best, and other times a fish has no chance of finding my bug on the water when there are, literally, millions of naturals riding the flow.

The hatch occurs anytime from late April through the end of May on most Inland Northwest and Rocky Mountain rivers (later on some Yellowstone area streams), just prior to (if you’re lucky) or just after (if you’re not) runoff hits in full force. When runoff arrives streams rise and turn clouded, meaning the color of black coffee mixed with two splashes of half-and-half. Place a fish a few inches below the lip of that latte, and you might see why trout have trouble finding these bugs in heavy, clouded flows.

But here’s the tradeoff for playing roulette—when conditions are right and this bug comes off you can catch scads of big rainbows and browns on size 14 and 16 emergers all afternoon long. The key to catching this hatch just right is to call daily to fly shops, guides and others in the know, checking on water conditions and the caddis’ presence. Again, when the two elements align, you’ll like the results.

This caddis, technically called Brachycentrus occidentalis, and also known as the Grannom, comes off on many waters, including Washington’s Yakima, Idaho’s Henry’s Fork, South Fork Snake, and South Fork Boise, and numerous Montana streams, including the Clark Fork, Madison, Missouri, Gallatin, and Yellowstone, among many others.

The timing of the Mother’s Day caddis means you may not deal with the hoards of anglers you might find on a given river during rush hour, meaning during June, July and August when everyone on the planet, it seems, wants to get their licks in. Instead, on a weekday in May, you might get a few runs, or a whole river, to yourself.

You can fish all day during the hatch, but the best time is during afternoons when these bugs may emerge in breath-through-your-nose masses. If you get to the river early you’ll want to fish pupae patterns, such as LaFontaine’s Deep Sparkle Pupa. Run a tandem rig with one pattern as the lead fly, and another attached to a two foot portion of tippet trailing the lead fly.

You’ll pick up some fish this way, but always keep your eyes open for the first emerging caddis. The trout tip you off to the emergence, too. When the bugs start popping you may see subtle rises, which indicates that trout are taking emerging pupae just under the surface.

The emerging pupae run about a size 16 and have green bodies and black wingpads. They don’t waste time getting to the surface so when matching the rising pupae, don’t be afraid to swing them at the end of your drift. This mimics a vulnerable caddis racing to the surface, trying to elude predators before hitting the surface film. This scenario is made for swinging soft-hackles, so don’t be afraid to whip out the trout spey gear.

Once these caddis hit the surface you can match them with emerger patterns that float half-in/half-out of the water. LaFontaine’s Emergent Sparkle Pupae is one of the most popular patterns out there, but many work. You can also fish your standard dries at this time, such as Goddard’s and Elk-Hairs. I’ve never seen the true dry outfish an emerger during this hatch, however, and I’ve been frustrated at times when I’ve tried to make it happen with a true dry and been snubbed. So think rising pupae and emergers during the afternoon hours and you’ll be good to go.

By late afternoon you may see the female caddis returning to the river to deposit eggs. Some land on the water and swim to bottom to attach their eggs to substrate; others just land and let go. In either case there is mega-mortality so fishing a spent-wing style crippled caddis, with a dead-drift and a slight twitch from time to time, is a good move. Fish it until dark if the bugs are still landing. You can pick up some good fish at this time, meaning the big, lazy boys that don’t work too hard for their meals.

As mentioned, this can be a difficult hatch to hit right, but you won’t forget it when the conditions and bugs align. I got that scenario one day on the Yellowstone, below Livingston, when nobody else was on the water. I couldn’t find fish in the big, main flow, but a couple side-channels were loaded with big browns that knew the bugs were coming. When the emergence happened I took a couple 20-inchers on emergers and many other fish in the 14-to 18-inch range. I’ve pulled off similar stunts on the upper Clark Fork near Deer Lodge, but I’ve also been handed my ass on the lower Madison—probably fished a dry fly when I probably shouldn’t have, meaning I threw an Elk-Hair Caddis when I should have thrown a pupae or an emerger.

Let’s say you know the caddis are coming off and you get to the river only to find it blown. Is it a worthless escapade? No way—if you get to see this caddis event—literally billions of bugs flying in the air at the same time, with red-wing blackbirds and swallows diving on them, you won’t forget it. It’s one of the West’s amazing natural phenomenons. Trout on the end of the line is the bonus.

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