We’re here for a good time, not a long time…

If you’d told me 20 years ago that I would be writing a piece extolling the virtues of the fishfly, I would’ve told you that you were crazy. As a child, I tried to get out of going to the cottage during the first few weeks of July, simply to avoid having to deal with these large, awkward insects that appeared in the thousands and stuck to everything. I would go to great lengths to avoid coming in contact with them and I couldn’t stand the smell that hung over the beach during those weeks that their bodies washed ashore, creating a putrid line in the sand.

However, here I am, much older and hopefully wiser, and an unapologetic fishfly fan. It was when I returned a few years ago to live alongside our great lake, that I discovered just how remarkable these insects truly are.

Whether you call them fishflies, mayflies or shadflies, these large-winged, long-tailed insects belong to the order Ephemeroptera, which literally means: ‘things with wings that don’t live very long’. It’s a fairly apt description if you only consider the adult form. With vestigial mouth parts and a digestive tract full of air, they’re lucky to last for more than a day. However, if you take into account the insect’s entire life cycle, they are actually relatively long-lived.

Here on Lake Winnipeg, our fishflies (mostly Hexagenia limbata) spend about two years as nyads (larvae), living in the sandy bottom of this immense, but shallow body of water. They’re detritivores, feeding on algae, diatoms and other bits and pieces that find their way to the bottom. They, in turn, form a large part of the food base for the numerous fish species that fill the lake.

Then, somewhere around the first week of July, an instinctual switch is flipped, sending the two-year-old nyads to the surface. Floating in the meniscus of the lake, their backs split open like a seam, letting the newly-formed winged morph  emerge. This stage is call the subimago and unlike any other order of insects, they’ll moult one more time into fully-fledged adults, all in the space of about a day.

It’s not so much the process that makes them remarkable, but the numbers. Lake Winnipeg, like many other shallow, fertile lakes and river systems, is home to millions of fishflies and they tend to show up all at once, carpeting everything: walls, roads, mailboxes, trees, lampposts, anything that’s standing still long enough for them to stick to. This mass emergence is their way of shuffling the genetic deck. It’s a nocturnal orgy of mating and egg-laying before everyone literally drops dead, their tiny bodies piling up under lights and along the beaches to be cleaned up by hoards of hungry gulls if the towns along the lake don’t get to them first with the front-end loaders.

Most people anticipate this yearly irruption with fear and distaste. I, on the other hand, look forward to it, because as long as there’s fishflies, Lake Winnipeg has hope.

Our lake is in trouble. Like way too many watersheds around the world, it is suffering from too much of a good thing: nutrients. An overabundance of phosphate and nitrogen are finding their way into the water, fuelling giant blooms of algae that, among other things, reduce the oxygen content of the lake both by using it themselves and by keeping it from reaching the bottom, where the fishflies live.

I fear for a fishfly-free summer. Thankfully, we’re not there yet and I’m optimistic that we can still turn the tide. Algae levels have been increasing for years, but public awareness has also risen and steps are being made to improve waste water treatment and watershed management. We have a very long road ahead, but as long as I keep finding fishflies stuck to my windows every summer, I’ll believe we can make it.

9 thoughts on “We’re here for a good time, not a long time…

  1. What a lovely post !

    At Trent University, in Peterborough, Ontario we had an interesting time with what we call Mayflies. Prior to our annual Convocation ceremonies we had the main building’s windows cleaned. Three stories of floor to ceiling windows. Can you guess what’s coming ? One year we had them cleaned and the next morning we came to work to find them all COVERED in Mayflies corpses !

    I too think they’re cool.

    • Thanks, Sybil! I’m glad to know there are other fishfly/mayfly fans out there. That must have been quite a blow to the cleaning crew, however to find them all there the next morning. I used to work for a resort that had huge windows and every summer was the same problem. They would also pile up under the lights on the grounds, but the gulls usually had them cleaned up within a week.

  2. They stick to windows too? This is a great post Heather, accompanied by a beautiful piece of art. I was unfamiliar with this fly, so you have enlightened me If I ever get to visit their habitat during this ‘ephemeral’ stage, I will know to appreciate them for their value as what I think you would call an indicator species.

    The more we can get the word out about the importance of watershed protection, the more people can act with knowledge and wisdom to prevent disaster. You do a great service with your blog and I appreciate it.

    • They stick to everything, Cindy! This fishfly in this image was sticking to a window when I took the shot. I’m glad you like the image. I enjoyed being able to take something that many Manitobans revile and turn it into something beautiful.

      You probably have some fishfly species. Manitoba has over 80 species. Not all emerge in such vast numbers at one time, so they tend to slip under the radar. I hope you get to experience them sometime. Smell notwithstanding, they’re pretty amazing.

      As for my blog doing a service, I fear I’m probably preaching to the converted, and it’s a fairly small congregation, but it’s good to get the word out regardless. Take care 🙂

  3. I have a great deal of catching up to do here, Heather, and this was a wonderful way to start: thoughtful, instructional and beautifully written. The ephemera of this world will linger longer through such intelligent storytelling. Thank you…

    • Welcome back, Julian! It’s great to hear from you. I’m glad you enjoyed it. I truly never thought there would be a day that would find me writing about fishflies.

  4. This is a wonderful piece Heather. I have always had a soft spot for fishflies because I found them to be tragic figures of the insect world – such a short life, they can’t even eat (now that’s tragic!) and then half of them end up in the spider webs all over our cottage and they don’t even get to enjoy that one night orgy. Tragic indeed. I have a special memory from a few years ago when I when for a swim at dusk and the water was dead calm. When I swam out a ways I found I was surrounded by a massive hatch of subimagos at the surface. Seeing thousands of delicate white bodies struggling out of their larval skins and flying off toward land was an ethereal experience I won’t forget. Yes they are smelly and make a big mess, but as you point out they are an important component of the aquatic ecosystem and have a certain poetic beauty. Thanks for a great post!

    • Hi Nancy. Fishflies, are kind of tragic in a way aren’t they? But, they’re not the only ones with short-live adult stages. Luna moths don’t fare much better and they are so much larger.

      That must have been an amazing experience being amount all those emerging subimagos. What an incredible moment.

  5. Pingback: Moonlight Becomes You « The Naturalist's Miscellany

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