Small winter stoneflies are an intrepid group built to emerge as adults in the winter. To survive the chill, they create their own antifreeze. In fact, they’re so acclimated to the cold that they estivate—which is like hibernating—in the summer.
Before moving on, a few words about names. What do most people notice about insects? They fly. But seriously, that’s no excuse for the rampant overuse of the word. It gets confusing. Here’s a quick guide:
If an insect is a fly in the order Diptera, the word “fly” is separated from its descriptor, like crane fly or soldier fly. If it’s not a fly, the word “fly” is incorporated into the rest of the name. Stoneflies, like butterflies and dragonflies, are not flies.
Stoneflies start their lives in the water, and the larger ones can spend three or more years there in a larval form called a naiad. In mythology, a naiad is a water nymph. Now there’s a perfect word to describe the nymph stage of a water-based insect!
Winter stoneflies in the Capniidae family eat plant material on the beds of streams and rivers. They make their own glycerol to keep their bodily fluids from freezing. According to Britannica.com, glycerol is an alcohol that is colorless and odorless but tastes sweet. Maybe cold water fish have a sweet tooth?
Adults emerge from the water in the winter. One reference I found said it’s possible to find their shed skins lined up on shore, looking like “pale little crustaceans.” That would be cool to see! They fly for just a week or two, find a mate, and then the female lays her eggs back in the water.
I saw this female near a small stream at Mt. Pisgah. It’s not a great photo, but it shows what I believe is an egg mass on top of her abdomen. I found a few other pictures online of females carrying eggs this way. No doubt, she was just hours away from laying them in the stream.
See more of Karen’s work here.
Michael Raupp’s column about winter stoneflies: https://bugoftheweek.com/blog/2014/3/17/winter-stoneflies-families-taenioptergidae-and-capniidae. Accessed 2/15/22.
A Scientific American blog: https://blogs.scientificamerican.com/guest-blog/winter-stoneflies-sure-are-supercool/. Accessed 2/15/22.