The Winter Stonefly: Our January Bug of the Month

When we think of “stoneflies,” our mind may go to late spring or early summer and bigger bugs, bigger patterns. Stoneflies, though, are another one of the insects that can be found in our tailwaters year-round. In the winter, anglers have to think small and think dark. The Winter Stonefly is our Bug of the Month.

The Low-Down on the Winter Stonefly

The winter stonefly is in the Capniidae family. While I usually don’t go into a lot of scientific info on this blog, the winter stonefly is worth a little discussion. These bugs actually produce their own anti-freeze – glycerol, sugars, and proteins ­– to allow them to thrive in colder temperatures.

There is not an emerger stage with winter stoneflies. While in the nymph stage, winter stones crawl onto the bank where they complete their transformation into an adult. 

The adult male seeks out a female by drumming his, umm, butt end on the snowy bank. The female drums back and they search out their mate. The bugs actually mate on the bank, on the snow, even when temps are in the teens. More abundant hatches can occur if the air temp reaches into the 30s. After mating, the female return to the river to lay her eggs. 

Want to dive deeper into the science of winter stoneflies? Chech out this article in Scientific American: Winter Stoneflies are Supercool.

How to Fish It

Winter stones are pretty much either dark grey or black. They can serve as a contrast to other patterns that you might be throwing — say, a red midge larva — and it is this contrast that will get a fish’s attention. In fact, as an option to fishing midges, a black winter stonefly can be productive.

In January, fish are in their low-metabolism, energy-conserving mode.  They aren’t going to move too far for a meal. In addition, since there are no big bugs in the water, an angler is going to have to go smaller. Since we are talking stoneflies, though, “smaller” in this case can range from 18 or 20s to 24s.

In terms of rigging, anglers have a few options.  Your first pattern might be an egg or San Juan Worm that can serve as an attractor.  Then your second pattern may be to “match the hatch.” While midges are often a great choice (they were our 2022 January Bug of the Month), a black winter stonefly can be a productive option. Shape and size is key! Water temp is important here. Midges will be active when water temps are below 40 degrees. As water temps rise, winter stoneflies are a better choice.

As with most winter approaches, fishing a deep hole is a good place to start. The winter window is often between 10:00 or 11:00 a.m. to about 2:00 or 3:00. As the water temps warm, and if a hatch is a bit more prominent, try fishing a stonefly higher in the water column or in shallower, faster riffles. In these shallower runs, anglers can let the weight of the beadhead, rather than a split shot, sink the fly. Then let the current do its work. Fish will move if the feeding opportunity exists!

I mentioned that winter stoneflies in their adult stages may be productive.  After they mate on the bank or snow, they move back to the river to lay their eggs. Under ideal conditions, more sun and warmer weather, fishing an adult could be really fun.

Tying the Winter Stonefly Imitations

Learn More

Winter fly fishing is often called “the secret season” because some folks don’t want to tackle colder temps and challenging conditions to chase sluggish fish. Why not take our Winter Fly Fishing class and learn the techniques to have a successful day on the winter water? Our next offering of the two-part class is January 20 and 21. Or take advantage of our Winter Rates for our Guided Trips and learn from one of our Orvis-endorsed guides!

If you haven’t done so, check out our Fishing Reports offering more in-depth intel on how to fish our local waters.