by Greg Thomas
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 won’t 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 afternoon, 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 can 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.
