Field Note: Stoneflies

By Rachel McKimmy

02/01/2020

My alarm wakes me up. My boyfriend is sleeping on the couch, Ford Lake a smooth gray mirror below the lightening pale-pink sky behind his head. We listen to Tom Petty on the drive to the Huron River Watershed Council, a few minutes late. It’s snowing lightly, disparate flakes drifting down from the sky.

The meeting room is packed full. The number of people willing to come out on a snowy Saturday morning to look for bugs, of all things, surprises me. Jason Frenzel, one of the bubbly leaders of the program, says this is their 26th year of doing the winter stonefly search.

My sketch of a stonefly nymph, with a ruler for scale. The ones we found were only the length of my fingernail.
My sketch of a stonefly nymph, with a ruler for scale. The ones we found were only the length of my fingernail.

Stoneflies, or rather stonefly nymphs, the larval stage of the insect we are looking for, are a benthic macroinvertebrate, a bottom-dwelling insect. The nymph is about the length of a fingernail, though some species can be up to two inches long. Antennae protrude from either side of the head, and like other insects the body is divided into segments from which six jointed legs emerge; and mirroring the antennae of the nymph, at the end of its body are two tails which are the stonefly nymph’s main identifier. 

This order of insects, officially called plecoptera, have been around since before the dinosaurs, and are an indicator species of water quality because they are especially sensitive to pollution. Hiding in rocks or leaf packs in streams and rivers, in debris caught against the flow of the current, the nymphs live; during the last winter of their lives, adults emerge with two pairs of membranous, veined wings. Their nymphal stage lasts from one to four years, only for the adults to live a few weeks. 

I hop into a car pool with three men. The leader of our team, an older man with a white beard and glasses who works as a statistician for pharmaceuticals, has done this for ten years. Another man wears a beard, a beanie, and a turquoise jacket. He works at an environmental consulting firm; it’s his first year participating. I ask them why they’re interested in doing this work. Shrugging, they answer that they just wanted to do something for the environment. 

The first site we visit is the intersection of Mill Creek, an offshoot of the Huron River which begins in Dexter, with Jackson Road. One of the brave members of our team wades into the icy water, collects a water sample, and starts scooping up viable stonefly habitat in a net for the rest of us to pick through with metal forceps.

Collecting leaf packs and rocks to search for stoneflies
Collecting leaf packs and rocks to search for stoneflies

Stonefly nymphs are distinguished from mayflies and caddisflies, other aquatic insects used as water quality indicators, by their two tails. Picking through the cold, muddy leaf-mush with my bare hands and what equates to a tiny pair of tweezers, my fingers turn pink and go numb. But I find stonefly after stonefly, squirming unhappily in the delicate grasp of the metal forceps, before they are dropped into a small bottle of alcohol to die and be preserved in the name of science and environmental health. Our goal is to collect as many as we can find in a certain amount of time, as an indicator of the health of this aquatic ecosystem. A couple fish would eat this many stoneflies in a day, meaning we’re not depleting the population enough to damage it, according to the leaders at the Huron River Watershed Council. 

 

Me, holding a bottle of stoneflies
Me, holding a bottle of stoneflies

Stoneflies are sometimes used by fishermen as bait because they are a natural food source for fish. Populations of stoneflies form one of the threads that binds the entire tapestry of the ecosystem together. Not only does a lot of the water we use come from rivers, but rivers and the habitats surrounding them, though small in size, support a lot of the state’s wildlife, making up some of the only forested space in urban and agricultural areas. Among the other creatures that make their homes in and around rivers are the blue-spotted salamander, the snowy egret, the painted turtle, the mudpuppy, the river otter. Each of these is a different piece of the puzzle. 

After this trip to catch stoneflies, I never got to follow up with my water quality work at the Huron River Watershed Council. My intention this summer was to visit the Great Lakes, specifically Lake Superior, for more ecological research. Because of the COVID-19 pandemic, I didn’t get to. So I shifted my focus to a water quality project with my independent ecology class this spring. This project focused on micronutrient contamination in the Huron River and Ford Lake and the effect of this pollution on waterside vegetation, and thus the quality of the riparian habitat. 

The Huron River, which flows into Ford Lake and from there into Lake Erie, is part of the Lake Erie watershed, which is the second link in the chain formed by the Great Lakes. I’ve always been fascinated by the flow of water, how it connects everything. The river near my mom’s house eventually flows into Ford Lake, behind the apartment where my boyfriend and I live. Water reflects how life eventually carries you from one place to another. It’s almost as if water represents time itself. And even the smallest details, the smallest creatures, can tell you a story about where they’ve been.