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What’s Purple, Sticky and Hangs in an Ash Tree? Emerald Ash Borer Survey Traps!

Posted by Sharon Lucik, APHIS Public Affairs, Brighton, MI in Animals Plants
Apr 10, 2018
Emerald Ash Borer trap hanging in a tree
Emerald Ash Borer trap hanging in a tree

Animal Plant Health Inspection Services’ (APHIS) Brian Deschu sets EAB detection tools (purple traps) along the roadside right-of-way as part of the national effort to survey for this invasive, tree-killing pest.

Like others across the country, Deschu is selecting suitable ash trees─those with enough height and girth and branches strong enough to bear an 8-pound weight. With an ash limb as a target, Deschu maneuvers the Barney trap (nicknamed for a certain purple-hued TV dinosaur) into place with a telescoping pole. This season, he’s hanging purple traps by the hundreds.

Setting a trap is part art and part science. Although every ”trapper” has a style that’s uniquely their own, precision, patience and manual dexterity are core skills. It’s almost artistry watching a seasoned trapper wrangle a 23-foot pole and drop a trap on its mark. Traps are hung in ash trees, trees of the genus Fraxinus, in the lower to middle canopy, at least five feet above the ground. When possible they are placed on the sunny side of the tree, most typically the south or southwest side.

The mechanics of the trap are simple and straight forward. In their adult stage, EAB beetles fly around ash trees, nibbling on leaves and looking for a mate. If an EAB lands on a purple trap it gets stuck in the glue. In mid-summer, survey crews return to the trapping sites to refresh the lure (which attracts the pest) and collect any insects stuck on the traps.  In the fall, the crews return to the trap sites a second time to collect samples and remove the trap.

With the search for the EAB in full swing, purple traps are appearing overnight in urban landscapes, public parks and along ravines and fence rows. Everyone is mobilizing for another season of EAB detection work. This year APHIS, along with state and tribal cooperators, are hanging 65,000 traps throughout the country. From Maine to the Gulf Coast and into the forests of Alaska, purple traps hang in ash trees─all told, 48 states are participating in the survey this year.

EAB is responsible for the death and decline of tens of millions of ash trees. Today the pest has been detected in 15 states: Illinois, Indiana, Iowa, Kentucky, Maryland, Michigan, Minnesota, Missouri, New York, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia and Wisconsin.

Category/Topic: Animals Plants

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Carter Hall
May 07, 2013

I don't know whether this is the same beetle that drives us crazy in the fall and winter or not. We have an old house and it is infested with these beetles every season. They leave during the summer months whe the trees come into bloom. They stink like the dickens when you mash one. I'd kiss someone if we could get rid of them.

Dave Bright
Jun 27, 2015

Sort of like closing the barn door after the horse gets loose isn't it ? There should have never been any wood imported in the first place.

Alain C.
Jul 17, 2016

Carter, the beetle you are describing is called a stink bug. They love to winter over in your home and can get through the tiniest cracks. They are nasty and are often found near some of their favorite food - corn and soybean, but they are also pretty well saturated. Tightening up your home with spray foam will help a lot. Over the last several years we have seen their number diminish. Good luck.

Apr 10, 2018

The link now seems to be for a topic completely unrelated to Emerald Ash Borers

Ben Weaver
Apr 10, 2018

@Ken - Thank you for letting us know. We have removed the link in the blog.

Apr 24, 2018

Would it be illegal to make and hang your own trap in an effort to lower the population?

Ben Weaver
Apr 25, 2018

@morgan - The EAB purple traps are used to detect EAB, not to reduce EAB populations. Also, the trap will not prevent EAB from attacking your ash trees. So, while homeowners can certainly hang traps for emerald ash borer it will not reduce insect populations. Here is a link about our 2018 EAB survey and the purple traps: (PDF, 127KB). If you are interested in more information about EAB, this is a link to our web site: and to the Emerald Ash Borer information Network:

kenneth Cutler
Jun 02, 2018

i have seen several ash beetles where i live how or where can i get these traps !!

Ben Weaver
Jun 07, 2018

@kenneth Cutler - The purple trap used to monitor for EAB can be purchased by homeowners online from various sources just by doing a quick internet search.  But, it is important to remember that the EAB purple traps are used to detect the presence of EAB, the traps are not a tool used to reduce EAB populations.

Oct 15, 2019

Yay Less of the bugs!