Stoneflies emerge early from streams

The days of mid-March show huge variations. During this time, we may shiver in the chill of single digits (even occasionally subzero) in the a.m., and in the lengthening sunlight of the p.m. we’ll bask in the sunny 50s or 60s.

Precipitation now may take the form of rain or snow. Melting and refreezing seems to be the regular occurrence. Dry and crusty snow on the ground in the mornings becomes wet and sticky later in the day.

Mid-March is also the time of awakening. Raccoon and skunk tracks that were mostly sporadic through the winter are now seen nearly every morning. The local chipmunks are out and scampering about. A few juncos and purple finches join the flocks of redpolls, chickadees, nuthatches and woodpeckers that wintered with us. And along the road, we may see a few hawks that hunt at these sites. Whether we tap the maple trees or not, the oozing sap is often found by the butterfly most early to rise from hibernation, the mourning cloak. Ants move about on their sunlit mound-cities while flies bask on the warm sides of buildings. But insects are active in plenty of other places as well.

Frequently at the edge of the melted snow circles that tend to form around deciduous trees in March, I’ll see movements of tiny black specs. Looking a lot like pepper on the light background, these minute insects cover the snow. But unlike pepper, these snow fleas, or springtails, hop about. The springtail name refers to an appendage they have on the underside the body to help jump in the snow. Despite the name, they are not fleas. Here too are a few crane flies out in the snow. Often called mosquitoes, they are common, but lack the mouth parts to allow them to partake in our blood. We’ll need to wait a bit longer to experience the mosquitoes that we are so proud of. However, another insect that has a water-beginning is emerging from the aquatics now, the stonefly.

The non-moving water of lakes, swamps and ponds in the Northland are still ice-covered and will continue to be so for a few more weeks. Meanwhile, the moving waters of the regional streams and rivers are breaking loose of the icy grip. Without a very cold winter, some places never really formed ice covers for the whole time. All of these watering ecosystems, whether moving or not, are homes to large numbers of insects. But a small black insect, the stonefly, now appears on the shores of where it spent the winter.

Since last summer, the immatures, known either as larvae or nymphs, have survived among the pebbles of the rapids — hence the name of stonefly. They joined young of several other kinds of insects: black flies, caddisflies and mayflies, to feed on debris floating in the stream waters. They remained active here all winter. Now in the very early days of spring, the nymph climbs upon a stream-side rock and triggered by the daylight and darkness length, it becomes an adult. The exoskeleton of the youth splits down the back and the adult insect emerges.

The adult is dark (perhaps an adaptation to survive in the chill at this site), but is complete with long antennae on the head, long tail-like appendages (cerci) on the other end, and six legs and wings in between. With emerging so early in the season, there are problems with the cold temperatures, but not many insect-eating birds are yet to arrive in the Northland. These early-rising stoneflies are likely to avoid avian detection. But they find each other, mate and deposit eggs again in the watery world of the stream. And after a rather short time as adults, the stoneflies die. However, by emerging in March, they propagate the species in the streams.

Retired teacher Larry Weber is the author of several books, including “Butterflies of the North Woods,” “Spiders of the North Woods” and “Webwood.” Contact him c/o budgeteer@duluthbudgeteer.com.

Tags: budge opinion, budgeteer, environment