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Vol 4.31   
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The larva of the Emerald Ash Borer makes S-shaped tunnels. Inset: The adult Emerald Ash Borer. Courtesy photos
Emerald Ash Borer Infestation Looming: Wasps to the Rescue?

REGIONAL – Since the Emerald Ash Borer (Agrilus planipennis) was first found near Saugerties, in northern Ulster County, in 2010, local officials and the Department of Environmental Conservation have been nervously watching for signs of the invasive insect's spread.

The diminutive, shiny-green beetles have become a national emergency since they invaded the US from China, probably in the wood of packing crates. Without their own natural predators to keep them in check, the Emerald Ash Borer (EAB) spreads and multiplies in colossal numbers. The larvae of the EAB hatch under the bark of ash trees and tunnel through the living part of the tree. Eventually the tree succumbs. The possibility exists that they will kill every ash tree in North America.

Now, the EAB has been found at the US Military Academy at West Point, Orange County and the DEC has responded by setting out a large number of purple prism box traps.

"We've increased our monitoring efforts, so that's why there are so many of the purple boxes out there now," said Michael Bopp, DEC spokesman. "It's an extensive effort to work out where the EAB may have got to in Orange County. It's surveillance, really, so that we can get better data on the footprint of the infestation. Once we assess what that footprint is, we can figure out what control we can put in place."

The purple prism traps contain two chemicals known to attract the EAB, as well as sticky glue so the insects are trapped. Michael Bopp said that there was a state wide effort underway by the DEC to understand where the EAB is at this point.

Survey in Ellenville
In Ellenville, meanwhile, a survey of the village's street ash trees was conducted by the Catskill Center for Conservation and Development.

Elizabeth D'Auria of the Catskill Center, said, "We only finished the inventory of the village trees on July 21. The objective was to get an idea of how many ash trees are in the village, so the village would know what they would be liable for. We found 25 ash trees that fit our criteria. These are just the trees in the public spaces, not in back yards or in the woods."

D'Auria then noted, "If and when the ash trees are infected with the Emerald Ash Borer, it will be expensive to deal with either way. Because the trees will die, and then become a hazard as their branches fall off. Either you take them down, and that means taking down mature trees in public space, which is never cheap, or you treat them with a pesticide, and that procedure costs as much as $1,000 per tree for large, mature trees."

D'Auria said that the EAB had been found in Saugerties, "towards Woodstock, or on the outskirts of Woodstock."

"It's very difficult to even slow the spread of this invasive," she added. "We are encouraging people not to move firewood, that's a big way that it spreads. We're trying to help towns and villages prepare for what is coming. No eradication program is taking place and we're assuming that it's going to go through every community in the region."

The Cavalry is Coming
The EAB is not a large insect, but it breeds by the billions once an infestation gets going. In Michigan it has killed millions of trees.

However, in its home range, in China, the EAB is not a particularly big problem, because there it is targeted by parasitic wasps. These are not the yellow jacket wasps we're all familiar with. These are tiny black wasps that seek out EAB larvae and lay their eggs on them. Then the wasp larvae eat the EAB larvae.

This summer New York, along with seven other states, will be testing these wasps, which will be released by the US Agriculture Department.

Two species of wasp are involved. Spathius agrilli, which is perhaps a third of an inch long, paralyzes the EAB larvae with a sting and then lays her eggs on the larval skin. The wasp larvae hatch and burrow into the EAB larva. The other is Tetrastichus planipennisi, which is the size of a rice grain. This wasp lays its eggs inside the EAB larvae, so has no need to paralyze it. Other Chinese parasitic wasps, such as Oobius agrili target just the EAB's eggs, and lay their own eggs beside them. They hatch before the EAB's eggs and eat the borer's eggs. The parasitic wasps are prey specific, they have been shown to target the EAB and nothing else.

During the month of August, the US Agriculture Department will release boxes of wasps to four locations in Ulster and Greene Counties, including sites near Saugerties and Lake Katrine.

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