Montana Fly Fishing Insects : Mothers Day Caddis

Mother's Day Caddis

Grannoms (Brachycentrus occidentalis)

Commonly known as the “Mother’s Day Caddis” or “little black caddis”, this constitutes one of the most important early season hatches on Montana’s rivers.

Grannom larvae build square cases out of aquatic detritus and attach themselves to rocks and thrive there until ready to hatch.

These caddis hatch when the water temperatures range between 48 and 52 degrees in the afternoons, which often occurs around Mother’s Day. At times this can be during runoff, but if runoff hasn’t yet happened, this can be an exciting hatch to fish.

Late April through early May - the exact timing varies yearly based on conditions - is when to plan a Bozeman fly fishing trip to experience the Mother's Day Caddis hatch. The hatch first occurs on the lower Madison River where anglers can expect a week or two of exciting dry fly fishing. The Yellowstone River warms up more slowly, but the bugs show up near Livingston a week or two following.

As the green pupa swim to the surface to hatch into adults, trout commonly target them since they drift in the surface film until ready to emerge, which can take up to 30 minutes.

The adults ride the water for a while until their wings dry and then fly off to mate. They’ll then deposit their eggs on the water, which usually occurs in mid-afternoons until dark. Trout will key in on these and are often acrobatic when chasing down adults as they emerge or deposit eggs from their emerald-colored egg sacs.

Imitate all forms of the Mother’s Day Caddis in hook sizes #14-#18. Adults are black with dark tan wings.

Fly fishing in Montana during the Mother's Day Caddis hatch is an experience worth adding to the bucket list! The sheer enormity of insects that hatch at one time is simply amazing and yes, the fish do actually eat with reckless abandon at times!

Contact Fins and Feathers in Bozeman to learn more or to book a guided fly fishing trip during this legendary Montana fly fishing hatch. We have been at it for 25 years and this is always a Montana fishing guide favorite hatch to fish with intermediate to advanced anglers.