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December 02, 2016
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Early fly hatch on the river

Stoneflies are not “high performance” flyers; they are relatively slow. Their flight enables them to breed in the spring and continue their lifecycle.

March 8, 2012

After visiting a friend at the hospital in Port Jervis during late February, I saw that it was turning into a fairly decent day outside; the weather was partly cloudy and the temperature was climbing into the high 40s. It was a good afternoon to drive up Route 97 and scout the river. I was mainly looking for eagles and other raptors. The first flying critters I spotted, however, were not birds at all, but a mass of flying insects. I had encountered one of the first fly hatches of the season on the river; the emergence of the black stonefly.

The black stonefly (Taeniopteryx nivalis) is one species of about a half dozen that reside in the river habitat. Stoneflies belong to the order Plecoptera, which translates to “braided wing.” As their name implies, they prefer stony bottoms of flowing rivers and streams. Stoneflies, like many other aquatic insects, hatch from the egg to the nymph stage. Depending on the species, they will spend one to three years as a nymph in the water. When they emerge as adults during early spring, they exit their water habitat and leave behind their nymph exoskeleton, much like a dragonfly. They will then mate and lay eggs to continue the lifecycle.

Black stoneflies are the first of the stonefly species to emerge from the river. Starting in the middle to late February, they can be seen in swarms over and along the river; they prefer mild afternoons with little wind. Stoneflies are food for fish, especially trout. Trout especially prefer the nymphs. Many trout fishermen carry artificial wet and dry flies simulating nymphs and adults.

If you see a swarm of stoneflies, stop somewhere safe and watch as they dance over the water and observe them close when they land nearby. They are not shy and don’t bite; you may even be graced by a few stoneflies that decide you make a good perch.