Purple traps enlisted in ash borer fight

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Gazette Staff
April 18, 2008
— State workers have yet to find any trace of the infamous emerald ash borer in Wisconsin, but they’re still trying.

The Wisconsin Department of Agriculture, Trade and Consumer Protection announced Monday that it plans to hang sticky, purple traps in ash trees in a number of counties, including Dane, Green, Jefferson, Rock and Walworth.

About 3,600 traps will be hung statewide, part of a nationwide effort paid for by the U.S. Department of Agriculture, according to a DATCP news release. About 60,000 traps are expected to be deployed nationwide.

The cost of the traps and the labor to deploy them in Wisconsin will be about $316,000, said department spokesman Mick Skwarok. The U.S. Department of Agriculture will cover $286,000 of that expense.

The tree-killing beetles of Asian origin have been found in northern Illinois but not yet north of the border.

Wisconsin officials hope to catch any infestation early, so they have a better chance of keeping it from spreading, Skwarok said.

Wisconsin workers began their search in 2006, using visual surveys. Later that year, they started stripping bark from trees to attract the ash borers and cutting down ash trees to see if they had been infested.

“The purple traps offer a less destructive and lower cost option” than cutting trees, according to the news release.

The three-sided traps are about 2 feet tall and little more than 1 foot wide on each side. Each one is coated with a sticky substance designed to ensnare adult beetles. They will be hung out of the reach of passers-by.

Each trap contains a lure containing manuka oil, the product of a New Zealand tree. The oil has been shown to attract ash borers and is similar to the chemicals that stressed ash trees exude. The borers also are believed to be attracted to the color purple.

Traps will be inspected after several weeks. In the fall, when the beetles are no longer flying, the traps will be collected and re-inspected.

About three-fourths of the traps will be placed in a grid pattern in 19 southern and southeastern counties that fall within 100 miles of the infestations in northern Illinois.

Other locations in the state that are further away, but still have some risk, also will be surveyed.

Seventeen seasonal employees are scheduled to start hanging the traps in the week of April 28.

Wisconsin is home to more than 725 million ash trees in forest settings and more than five million in cities and villages.

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