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Sun., Aug. 30
Serving the communities of Massena and Potsdam, New York
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Caddisflies are missing from Ogdensburg, and no one really knows why


You might not know the technical name for them, but with all St. Lawrence River springs come swarms of Caddisflies filling the skies with the rustling of millions of tiny wings.

But those swarms of bugs known locally as “shadflies” aren’t where they used to be, and experts aren’t sure of the reason.

Clarkson biology professor and Director of the Great Rivers Center Michael R. Twiss said caddisflies are an important part of the region’s ecosystem and an excellent way to judge the water quality of local rivers.

Because the bugs are extremely sensitive to pollution levels in the water Mr. Twiss said, “The fact that they’re in the water is good because it means the water quality is really good.”

Yet caddisfly populations are not evenly distributed throughout the region. This year has seen swarms of them in Lisbon, for instance, but only a few in Ogdensburg.

Sallie McDonough Planty, an Ogdensburg native and a seasonal resident of the city, said she remembers an Ogdensburg Maples baseball game in the late 1940s or early 1950s that was called off thanks to a shadfly swarm.

“This was a night game. We got out there at Father Martin Field – which we called Winter Park at the time – and the [shadflies] were so thick they had to call the game.”

Shadflies are no longer as thick in numbers in the city as they once were. Mrs. Planty said she remembers as a child business owners having to sweep their bodies out of doorways and shovel them off city sidewalks. She said she wonders every spring where the shadflies have gone.

Mrs. Planty is not alone.

Steve F. VanderMark, a retired St. Lawrence County Cornell Cooperative Extension natural resources educator and entomologist, said that unfortunately, there hasn’t been much study focusing on caddisfly populations.

He said he still has a few educated guesses about why their numbers have declined in and around Ogdensburg.

He said it’s possible, for instance, that the Ogdensburg population may just have a more spread out emergence now thanks to weather conditions that are slightly different than they were in the 1940s and 50s.

It’s also possible that the caddisflies in Ogdensburg were simply blown away by gusty conditions one year and haven’t yet repopulated the area in the same large numbers.

Another possibility, Mr. VanderMark said, is that the lights of the city drew them inland over the years and they failed to make it back to the water to lay their eggs, slowly killing off the local population.

The worst-case scenario, however, is water pollution, Mr. VanderMark said. “Could they be telling us something?” he said.

Mr. Twiss said the water quality of the St. Lawrence River is not closely monitored, and perhaps the caddisfly depopulation is an early warning sign.

“They can be used as a water quality indicator,” Mr. Twiss said. “If they’re missing, there could be a reason they’re not around. People are right to be concerned about it.”

But their numbers are still strong in Lisbon and through to Red Mills, said Lisbon native Michael J. O’Neil, director of Lisbon Beach and Campground.

Mr. O’Neil said he remembers having to sweep them off the porch of his St. Lawrence River camp when he was young, “just like sweeping snow off your steps.”

Shadflies are interesting bugs for several reasons, Mr. VanderMark said. To begin with, caddisflies differ from real shadflies (also known as mayflies) in several ways, the most notable of which is their wings.

Caddisflies have tent-shaped wings while shadflies hold their wings over their backs like sales on a boat, Mr. VanderMark said. Shadflies also don’t emerge in large clouds like caddisflies do, and caddisflies spend most of their lives underwater as larvae.

Mr. Twiss said the caddisfly, which doesn’t have a functional mouth, only emerges from the water as a flying insect to mate, lay eggs and die.

“They’re just built for sex,” he said, adding that the reason they emerge in such great numbers all at once is so they are certain to reproduce even if a large number of them are eaten by fish or killed by passing motor vehicles.

State Department of Environmental Conservation officials could not be reached for comment on their water quality monitoring activities or whether any studies are being done on caddisfly population changes.

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