Insect invasions

I find it fascinating how certain insects get into this country.

For example, a story that was told to me – though I don’t know for a fact that it is true – was about corn borer moths and how they got from Europe to our country. It is a simple story of a group of moths hopping a ride on a passenger plane, which happened to land in Chicago.


European corn borers running amok in our corn. OK, this is very simply stated, but we do have another pest that we are concerned about and one which also hopped a ride over to the U.S. in some way or another – the Emerald ash borer. This insect is native to northern China and also to Korea.

It was first found in Michigan in 2002 and since has found a great place to live and do all the things that this borer likes to do. Thus, it has since spread to other parts of the U.S., which include Ohio, Indiana, Maryland and the latest state to be dealing with it is Illinois.

It has spread very quickly for an insect that only moves roughly a half mile per year. Humans have been inadvertently helping it out by unknowingly purchasing firewood or other wood products that have been infested with this borer. Because of humans inadvertently helping out this little pest, it has now made its way into Minnesota.

At this time, we do not have it in southwestern Minnesota. It has been found in the Twin Cities area and in southeastern Minnesota.

In 2008, inspectors had found firewood that was distributed by a company that was brought from Illinois to Minnesota that had Emerald ash borer on it. Minnesota currently has approximately 870 million ash trees, which this insect pest would indeed, find tasty. It is important to Minnesotans to know what to look for since we do cherish our timbered land and also the ash trees that adorn our own yards and what to do if we think that we have an ash tree that is being used as lunch.

So, were do we begin? The first thing to do is that if you go camping, don’t transport firewood. Emerald ash borer lives under the bark of the ash tree so it may not be evident. We need to learn what Emerald ash borer looks like. It is about one-third to one-half inch long and iridescent green. It is actually a very pretty insect if it just wasn’t such a bad bug.

There are a couple of insects out there that may be confused with it, so it wouldn’t hurt to double check on what it is that have for sure. An ash tree that is infected with this bug will have thinning foliage and some dieback at the crown or in the crown of the tree. Emerald ash borer infested trees will die quickly.

They do not pick out the unhealthy ash trees from the healthy ones. They pretty much eat any kind of ash tree in any kind of condition. The larvae of this insect tunnel under the bark which interrupts the flow of water and nutrients, thus killing the trees.

If you see an insect in Minnesota that you think could possibly be the Emerald Ash borer or you find an ash tree that suddenly begins to die, contact the Minnesota Department of Agriculture on their Arrest the Pests Hotline at 1-888-545-6684 to report it.

You can also report it at a local level to your local Extension office for identification. The Extension also has more information that they can hand out to you upon request.

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