A little more than a week ago, a friend who resides in Fulton County emailed his fishing buddies to report “the sulphurs are hatching.” To a fly-fishing enthusiast this signals a chance to do some exciting dry-fly fishing.
To the uninitiated, dry flies are imitations of adult insects that float on the surface of the water rather than nymphs, the larval stage, which live below the surface. When a trout slurps up a dry fly it usually gives the angler a jolt of excitement.
When the “hatch is on” this means the bugs, in this case mayflies, are emerging — changing from the larval stage and coming to the surface and fly off to fertilize and lay eggs for another generation. This is when trout go on feeding frenzies. When a hatch occurs hundreds and thousands of insects hatch at once. The volume is expected because a female mayfly may lay upwards to 8,000 eggs in the water after mating.
“Sulphurs” are just one part the hundreds of species of the Order Ephemeroptera — meaning short-lived. A mayfly’s life cycle is complex. Eggs are deposited on the bottom of creeks or lakes. Hatching as nymphs (larva), the insect will live underwater for one to three years, depending on species. They feed on algae and other organic matter. When the time comes the nymphs transform into sub-imago, commonly known to anglers as “duns.” The dun rests on the surface of the water until its wings dry and then flies away as an adult.
The adult’s only goal is to find a partner and mate because it will die in less than 24 hours. Some species of mayflies do not even have mouths or digestive systems.
During the hatch the mayflies swarm over the surface of the water. Look closely and one will see the males diving up and down seeking a partner, and the females will fly a straight line until caught by a male. After mating the mayflies die and fall on the water. Anglers know this stage of the lifecycle as “spinners.”
Motorists may have experienced “a hatch” when bugs splatter and mess up a clean windshield when driving in the vicinity of a creek or other body of water. In Minnesota mating mayflies have been known to cause car crashes when they die, fall and pile up 4 inches deep on the highway.
Trout feed on the nymphs on the bottom or those that cling to rocks. But the fish really go wild when the hatch is on. This is when the mayflies are most vulnerable. As duns they struggle on the surface as their wings dry. Females fall prey when they settle on the water’s surface to deposit their eggs. Both males and females are gulped down by the trout when they die and fall as spinners.
The object of the angler is to match the size and color of the insects hatching. In our case, the sulphur (also known as a Pale Evening Dun) generally hatches on Pennsylvania streams sometime between May 20 and June 20. When the hatch occurs it is usually in the evening, mostly around 8:30. As a dun, the insect has a creamy yellow body, almost white. The spinner body is orange or tan with clear wings.
Local anglers may know the nearby Codorus Creek has a sulphur hatch.
In our case, Thursday we drove to Fulton County to fish. We knew we were late into the hatch and with a moon approaching full we did not know what to expect. As it turned out, we watched only a few straggling sulphurs flying, looking for mates. Our imitations convinced a few trout, but we were too late for the real action.
We vowed to make an effort to keep the calendars clear around late May and early June next year to await the call: “The hatch is on!”