On my way down to a favorite steelhead pool, I was amazed to see a small, whitish, insect flying between snow covered branches of a fir tree. A hatch? In the snow?

A closer inspection showed that it was a winter moth, an interesting inhabitant of the coastal forests in the Pacific Northwest. As it blundered through the air, it wasn’t hard to imagine it falling on the water - and enticing a steelhead or big resident rainbow to rise.

There are two kinds of winter moths in the forests of British Columbia. The Large Winter Moths (Paraptera danbyi) whose larvae feed on Picea spp, and the Small Winter Moths (Oporophtera bruceata) whose larvae feed on Saskatoon (Amelanchier alnifolia) and snowberry (Symphoricarpus racemosus).

Winter moths are fascinating insects. At a time when most insects have settled into a state of suspended animation, winter moths are just emerging from their cocoons or pupae. A dense "fur" coat, similar to that seen on bumblebees, is among the adaptations which help keep these moths warm through winter months.

And when it gets particularly cold, they simply crawl under leaves and wait for a warmer day to be out and about. Coincidentally, those warmer days are often the best times to be fishing, so stay alert next time you are fishing, and see if you can spot a moth.

To fuel flight in winter months, these moths feed on sap that oozes from broken branches, broken tree trunks, sapsucker holes, or cuts made by hungry red squirrels. Moths that are still alive in April can also be seen feeding on pussy willow flowers.

In late winter mating takes place and eggs are laid near buds of host trees. The caterpillars hatch in early spring, at about the same time that the first leaves are emerging from the buds. They feed till the summer, and then build a cocoon in which the pupae will spent the rest of the summer and fall months in a kind of summer-time hibernation known as aestivation - waiting for the cold of winter to make their appearance as adult moths. This is the reverse of the survival strategy used by most insects - but it works for them. One advantage is that there are far fewer birds around to snap them up.

We don’t have any reports of trout or steelhead rising to take winter moths, but it only makes sense that hungry fish would take one of these “attractor” flies if they ever got the chance.