What are those purple boxes?

Emerald Ash Borer
Emerald Ash BorerCourtesy USDA
Driving around Saint Paul recently I’ve seen purple boxes hanging from trees, and I wondered what the heck they were. My wife helped me connect the dots between the purple boxes and the emerald ash borer (see ARTiFactor’s article for more info on the emerald ash borer). The Department of Agriculture and the Minnesota DNR is hanging the purple boxes to track and monitor the bugs.

We use a similar system in the museum. There are bug traps placed all over the museum that are not intended to eliminate bugs, but more to trap some so we know if bugs are in a certain areas of the museum and what kind of bugs they are.

The mailbox-sized trap’s color and smell attract the bugs and allow for tracking. The boxes will be removed this fall. Bark has also been removed from two dozen unhealthy trees in order to trap and track the pests. These trees will be cut down this fall as well.

The emerald ash borer is very difficult to detect. If you have an ash tree in your yard you can check for infestation by watching for die-back in the upper third of the tree, heavy activity by woodpeckers, D-shaped holes in the bark and S-shaped grooves under the bark. If you are a Saint Paul resident and notice these signs you are encouraged to call the forestry office at (651) 632-5129 if the tree is on public property and (651) 201-6684 if the tree is on private property.

I have also seen a massive number of billboards and heard radio ads from tree care companies promising treatment and protection from the pests. However, forestry experts indicate that there is no proven method for eradicating them.

The City of Saint Paul is preparing presentations for local district councils on what the City’s next step and what steps they can take to help. Several Saint Paul neighborhoods are potentially going to be especially hard hit as ash trees were popular with developers in post World War II neighborhood developments.

Updated information on the emerald ash borer for Saint Paul, Minnesota residents.

Your Comments, Thoughts, Questions, Ideas

JGordon's picture
JGordon says:

Argh. I've been putting coins in those. No wonder nothing happened.

posted on Mon, 06/22/2009 - 10:49am
Thor's picture
Thor says:

Just read in the Fix-It column over the lunch hour that a tree with the purple bag doesn't necessarily have the Emerald Ash Borer in it. The tree was just picked for its location. We don't want to incorrectly label uninfected trees as being infected.

posted on Mon, 06/22/2009 - 2:26pm
Anonymous's picture
Anonymous says:

I just noticed one yesterday and thought it was a box kite that got caught in a tree.

posted on Mon, 06/22/2009 - 3:16pm
Joe's picture
Joe says:

Thanks Thor, I didn't mean to imply that the boxes indicated an infected tree, rather they are placed around for monitoring purposes. Sorry if I was confusing.

posted on Mon, 06/22/2009 - 4:30pm
keithbraafladt's picture

Keith @ SMM.org
Wonderful post! just had the same conversation with my wife can the Buzz have an electronic billboard with posts like this? ...!

posted on Tue, 06/23/2009 - 5:07pm
arbordoctor's picture
arbordoctor says:


You are giving the people no hope on saving these trees. I think you are listening to the wrong people when it comes to saving ash trees. The treatments are effective if done right. I have been talking with a tree service that is based out of Michigan. Right in the war zone for these insects. We have not seen anything yet when it comes to Emerald Ash Borer.

He has been treating ash trees for the past 5 or 6 years to the tune of 20,000 trees in total. He has even treated entire cites of ash trees. To date he has lost 2 trees. Do the math. That is a survivla rate of 99.99%. Now tell me that treatment is not effective. He uses the same method as me which is a company called wedgle.

Arbor Doctor

posted on Wed, 09/15/2010 - 12:45pm
bryan kennedy's picture

Hey Bryan,

Do you know of any specific municipalities that are considering these sorts of treatments. I'd be curious to know the specifics. Do you know if any city arborists in Minnesota are considering this treatment?

I know at least in my neighborhood, the assumption is that we will loose all our ash trees. At some level a city might just have to make a decision to cut the trees down, right? As far as I understand these treatment programs require constant upkeep, because once the little bug is in our area it can infest the tree at any time. What's the average cost per year for a treatment like that?

posted on Thu, 09/16/2010 - 10:13am

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