Every Canadian gamefish gobbles up mayflies. Here’s what anglers need to know


Everything—absolutely every sport fish that swims—eats mayflies. They are protein-packed bundles of gooey good nutrition, and every fish from walleyes and whitefish to northern pike and muskies gobble up mayflies every chance they get. And for the next month or so, they are going to be millions, even billions of mayfly larvae spread across the bottom of our favourite lakes. Especially important is the biggest, most delicious mayfly species, the giant burrowing hexagenia limbata.

We spent time the other day on our Doc Talks Fishing podcast with our good friend, retired OMNR biologist, Bev Ritchie who studied the relationship between walleyes and mayflies in Savanne Lake, out of the OMNR’s Walleye Research Unit. Bev discovered a number of remarkable things. Most noteworthy is the fact that the peak hatches occur in the spring of even numbered years (like this year). Bev also discovered that walleye and yellow perch eat so many mayflies when they’re abundant that it reduces cannibalism—especially on young-of the-year walleye—so that’s when we typically record our best walleye year classes.


“They mayfly larvae have tusks they use to dig out burrows,” Bev explains. “They also have gills, so they survive by getting air from the water. And they feed on detritus—organic matter they break down.

“Mayflies are like caterpillars turning into butterflies. They require a number of moults from egg to caterpillar to butterfly. It can be upwards of 30 to 40 different moults as they get larger. And mayflies are largely aquatic for that two-year period. They dig a U-shaped burrow in the substrate, and two years later come to the surface and emerge as the mayfly.”

An adult Hexagenia limbata mayfly (photo: James St. John/Flickr)

Amazingly, as Bev explains, the beautiful adult mayfly only lives for one to three days, with its sole purpose being to reproduce. The adults don’t even have mouths, so they don’t feed. “The males swarm and the females find them and go through a reproductive process. They typically stay within one to two kilometres of where they emerged,” Bev says, which explains why we most frequently see the adults blanketing the windows of buildings and lamp posts near the water’s edge.


What’s even more fascinating is that immediately after our podcast with Bev went to air, we received a message from our friend, Mike Chau. We first met Mike two years ago, when he sat in on one of our ice fishing seminars at the Spring Fishing & Boat Show in Mississauga, Ontario. Mike and his buddies were keen to get into some whitefish action, so we shared our experiences, tips, tricks and techniques.


But get this: As soon as the podcast with Bev aired, Mike sent us a some images of the gorgeous whitefish that he and his buddies had caught only two days prior. And how did he find the fish?  You guessed it. He spotted dense clouds of mayfly larvae on his sonar unit, suspended in the water column, struggling to reach the surface before being eaten by the whities.

To learn more about the miracle of mayflies, you can listen to the entire podcast with Bev Ritchie on your favourite provider or simply CLICK HERE.