Last year we took a Good Natured look at the mayfly, one of a cast of assorted characters often lumped together under the generic term “river bugs.” We talked about the delicate beauty of the adults; the fleeting nature of that final life phase; and the insect’s vital role in local food chains. We also mentioned a little bit about the immature life stages—how the nymphs breathe through gills and require clean, well-oxygenated water in which to survive.
In preparation for that column, I went to Ferson Creek and poked around underneath the rocks in the streambed. My hope was to find a mayfly nymph to photograph. While a lot of people might be familiar with the adult mayfly, far fewer have seen the amazing, intricate details of the juveniles. What better way to learn than by seeing a picture?
Alas, I succeeded in the first half of that mission, but not the other. The little guys were there all right, but their small size, combined with my limited photographic skills, resulted in a series of blurry images that made the beautiful river rocks look like potatoes, and the little nymphs—so wonderfully detailed in real life—like the black spots you cut off before baking.
The piece that ran last year included a photo I’d taken several years before, during a mayfly hatch in 2010. However, I never gave up on my dream of one day photographing a baby mayfly.
Little did I know that all I needed was the help of a first grader.
A few weeks ago, during summer nature camp, I was hanging out with a group of Pathfinders—our program for kids entering kindergarten and first grade. We were at Ferson Creek Park, and the campers were dipping their nets into the silty softness of the stream bottom where it meets the Fox River.
All of a sudden, one of the kids let out a squeal. From where I stood maybe 20 feet upstream, it was hard to tell if it was a good squeal—one signifying discovery—or a bad squeal, as in the sound a kid makes when s/he gets pinched by a crayfish.
Turns out, this squeal was a combination of the two. Ian, one of the more intrepid Pathfinders, had pulled his net out of the water and found something unlike anything he’d ever seen before. An inch and a half long, with appendages poking out at all angles, the creature could be either friend or foe. Ian wasn’t taking any chances; he just focused on squealing—a sound that brought his instructors and I sloshing over to intervene.
Ian was more than happy to surrender his net so that we could figure out what it was he’d caught. You’d think at that point that things would have quieted down. But, no. When Ian’s squeals died down, well, that’s when mine started up.
Because what he’d found was a mayfly nymph, one from the family Ephemeridae—the common burrower mayflies.
I know, cool! Right?
The Ephemeridae adults are our area’s largest mayflies, with bodies lengths of up to 30mm—a little over an inch, for those of us who don’t speak metric.
This family’s offspring are no slouches either. With long bodies, beefy forelimbs and sharp mandibles that look like tusks, the nymphs are impressive indeed. Add on a pair of long, fringed antennae, feathery gills that line the outer edges of the abdomen, and three filaments trailing off the back, and you’ll quickly understand why Ian, and I, were squealing.
Ephemeridae, it seems, can cause a sensation wherever they occur. Even if you haven’t seen one in person, you’ve probably heard about them. Remember last summer, when millions of mayflies emerged en masse from the Mississippi River near LaCrosse, WI? They were Ephemerids, genus Hexagenia.
I recall Tom Skilling talking about them on WGN. The clouds of insects were so thick, they actually appeared on weather radars. In fact, the roads became so slick, cars collided on roadways nearest the emergence. But just as quickly as they arrived, the insects were gone again. All that remained of their ephemeral lives were there somewhat more durable exoskeletons—which had to be cleaned up with snowplows and shovels.
TriCity mayfly emergences do occur, but on a much lesser degree. Our waters aren’t quite up to the high standards needed to support large numbers of mayflies. Which means it’s important to conserve every nymph we find.
Including Ian’s. After a brief photo session that involved some fresh water, a baby-food container and more than a little bit of luck, we let the immature mayfly go back to its burrowing ways.
Like its adult phase, the nymph’s time with us at summer camp was short. But our memories of it, along with some so-so, though not awful, photos will last a lifetime.
Pam Erickson Otto is the manager of nature programs and interpretive services at the Hickory Knolls Discovery Center, a facility of the St. Charles Park District. She can be reached at 630-513-4346 or potto@stcparks.org.
August 14, 2015
Mayfly Nymph
This burrowing mayfly nymph’s sizable body, beefy limbs and tusk-like mandibles, combined with three cauda, or “tails,” and an impressive set of feathery gills along its abdomen, caused plenty of squeals at Ferson Creek Park this summer.