The Dreaded Fly Hatch
By: Mark Romanack
The Giant Mayfly is a common food source for a wealth of fish species.
In this part of the world a specific insect hatch occurs that boggles the imagination. The annual mayfly hatch is something some anglers look forward to and others dread. While the Great Lakes region is home to over 100 different species of mayflies, it’s the largest species the Hexagenia limbata that gets all the attention. Commonly called the giant mayfly or fish fly, this species of mayfly can be found near lakes and slow moving streams.
Ironically, the best known species of mayfly does not hatch in May, but rather in June and early July. Hatches normally occur on calm nights and literally countless millions of these delicate insects burrow out of the lake or river bottom as a larva, swim to the surface and emerge as a winged adult.
The adults mate in flight then the female returns to the water surface to lay her eggs. After depositing her eggs, the mayfly dies and floats on the surface of the water. Meanwhile, the eggs sink back to the bottom where they will remain until next spring when they hatch. Once the eggs hatch into nymphs they burrow into the bottom where they will remain for approximately two years before the cycle repeats itself.
Anglers who target trout like this brook trout will find that during the annual mayfly hatch fishing can be exceptional. A huge percentage of the annual food intake of the brook trout centers on aquatic insects like the mayfly.
A wealth of fish species depend heavily on the mayfly hatch to provide a critically important protein source. Some species of fish actually root the nymphs right out of the mud, while others wait to feast until the adult nymphs emerge from the bottom and swim to the surface. Still other species eat the adult mayfly off the surface while they are emerging and also while the flies are laying their eggs. Even after the mayfly dies and floats on the surface, they become easy pickings for hungry fish.
Mayfly in their various stages make up the majority of the diet for many species of trout. Fly fishermen who target trout wait patiently for the mayfly hatch to take place as it sets the stage for some of the most exciting fishing action of the year.
Popular fly patterns that imitate the nymph stage (wiggler), the emerging adult stage (dun) and the dead or dying stage (spinner) are all used to fool trout.
While trout fishermen benefit greatly from the mayfly hatch, anglers who target other species are commonly saddled with very tough fishing conditions. Walleye anglers for example know that when the mayfly hatch is in full swing, fishing success is typically going to be very poor. It’s tough to get a walleye to bite conventional lures and baits when they are swimming around with a stomach that is literally stuffed full of mayfly larva.
Some species like walleye can become very difficult to catch during the mayfly hatch.
So some anglers swear by fishing during the mayfly hatch and others swear at these annual insect reproduction cycles. In the big picture, the fact that we have huge hatches of mayfly is a good thing. Mayfly are delicate insects that can only survive in waters that are pollution free and waters that feature an abundant supply of dissolved oxygen.
So the common mayfly is an important indicator of the quality of our environment. If you’re an avid trout fisherman, the fly hatch is something to behold. If you’re a walleye angler, the fly hatch is a good reason to take up trout fishing!
Alas, the mayfly hatch only lasts about two weeks. After the hatch, things in the world of fishing return to normal again. As they say, this too shall pass.