Scouting for the Hemlock Woolly Adelgid in Rochester

There are a number of invasive insects that environmentalists are tracking, but this year there’s some extra attention on the Hemlock Woolly Adelgid (HWA). This invasive insect feeds on the sap of eastern hemlock trees and its well past becoming a nuisance. It spreads at such high rates that it currently is on track to decimate New York’s hemlock population. This time of year is a critical point in the insect’s gestation, so we went to see if we could locate any infestations in Rochester. Unfortunately, it didn’t take long at all. We found egg sacks within just minutes of stepping into Washington Grove near Cobbs Hill Reservoir! Why Hemlocks Are Important To truly understand the potential devastation the Hemlock Woolly Adelgid might cause, it’s important to understand why eastern hemlocks are so critical. Eastern hemlock trees are what’s known as a foundation species. A foundation species is a local species that is plentiful, but most importantly it controls the ecology immediately surrounding it. In the case of the hemlock, one way they are critical is how their root systems help stabilize cliffs in our gorges. You’ll see examples of this throughout Watkins Glen State Park and Taughannock Falls State Park. If those hemlocks at the edge die, their root systems no longer provide the structural integrity for the soil. That could ultimately mean crumbling gorge walls. Hemlocks also provide an ample tree canopy. That shade assists with controlling the temperature in those forests allowing other plants and forest life to thrive. As the third most common tree in New York State, the eastern hemlock’s absence would devastate much of our natural landscape. The tree is so prolific here that if the hemlock was suddenly erased overnight, you wouldn’t even recognize most of the scenes you’re familiar with in the Finger Lakes. If you’re thinking that just replanting more hemlocks would solve the problem, there’s trouble with that solution. Eastern hemlocks are also known as a climax species, which means they are an indicator of a mature ecosystem. It can take hundreds of years for them to reach a state of maturity. How the Hemlock Woolly Adelgid Causes Destruction The Hemlock Woolly Adelgid first made its way to North America in the early 1950’s by way of Japan. The first place it was spotted was in Virginia and in the 70 years since it has spread to nearly half the country. Back in Asia the adelgid has natural predators that help keep the balance. Here in the United States though, there is nothing to stop the bug, so reproduction continues unchecked. The adult HWA is super tiny. In fact, it’s about .8 millimeters wide. (For reference, the width of a human hair is about .12 millimeters.) Imagine walking through the woods and trying to spot a hair laying on a branch in a tree! Needless to say, spotting an adult is nearly impossible with the naked eye. As an adult, the HWA is asexual so it can reproduce without the […]

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