Winter is a decidedly quiet season. A fresh blanket of snow can send a hush over the landscape, plus fewer of us are out and about during the coldest months of the year. One more thing contributing to the quiet: Not many insects are out there buzzing, chirping and trilling. One notable exception to this is winter stoneflies, an insect that thrives in the cold. 

The winter stonefly is not one particular species of insect. Instead, it is a group of insects belonging to the Plecoptera family. Thousands of stonefly species can be found across the world. In Illinois, 21 species of winter stoneflies have been documented, but some are now considered extirpated and typically only a small number of species have been documented per county, according to the Illinois Natural History Survey.

As winter creeps in, stoneflies prepare to complete their life cycle and emerge from the frigid waters where they lived as nymphs, according to Metroparks Toledo. They don't live long as adults, only a few days or weeks. During this time, their only responsibility is to mate to start their life cycle anew. 

Like many insects, including crickets and cicadas, stoneflies make noise to an attract a mate, but unlike those insects, the sound stoneflies make cannot be heard by humans. The males will drum their abdomens on the ground, a perch or other surfaces to attract the attention of a female, and the female will respond by drumming in return, according to Metroparks Toledo.

After mating, the female winter stoneflies will lay their eggs in icy waters or on ice, Friend of the Rouge River reports. The eggs hatch, and the insects will spend most of their lives in the water in the nymph stage. In the summer months, when the water is warm, the nymphs typically burrow into the muddy bottoms and enter diapause, a hibernation-like state of decreased metabolic activity. Once the chill returns to the water, the nymphs become more active. They can remain in the nymph stage for as long as three years before emerging into the cold winter air as adults. 

Because stoneflies require clean, fresh water to complete their life cycle, their presence is an indicator of good water quality, Metroparks reports. They cannot survive in polluted waters or without access to water with adequate oxygen levels. In the water, they also serve out their other ecosystem role as prey for fish and other aquatic animals that eat insects.

Stoneflies aren't a common insect, and adult winter stoneflies aren't encountered all that often. Their physical appearance can vary from species to species, but they are typically dark in color with thin bodies that are about a half-inch long. 

Stoneflies mostly fly under the radar because they don't bite or sting or pose any harm to humans, and they also don't intrude in our homes, according to the Michigan State University Extension. And while they do fly under the radar, they are capable of flight. Adult stoneflies have wings, although they are not strong flyers and do not usually travel far from the water from which they emerged.

Your best chance of catching a glimpse of a winter stonefly is near the waterways from which they emerge. After leaving the water, they will find a spot to perch so they can molt and dry out, Metroparks reports. When they perch on snow or ice, the contrast of their dark color might catch your eye. The dark color also absorbs sunlight, keeping them warmer in the winter air.

Absorbing sunlight isn't the only way these insects avoid freezing. Their bodies also contain glycerol and other compounds that function like antifreeze, preventing them from freezing to death.