By Joe Sebastiani, Seasonal Program Team Leader
This summer, my wife and I took a road trip to Ohio and Michigan. Along the highways and in all the forests we explored, almost every Ash tree was dead or dying. The cause? Emerald Ash Borer, a small green-metallic beetle originally from Asia which was accidentally imported into Michigan. The adult insect feeds on Ash leaves, but the wood-boring larvae feed on and damage the inner bark and phloem, killing healthy trees in 3 or 4 years. I can’t help but think of the loss of American Chestnut due to the introduced Chestnut Blight 100 years ago, reducing this once gigantic widespread tree to small, scrawny saplings in our woods.
Among a forest of dead Ash trees at Magee Marsh Wildlife Area, near Toledo, Ohio, we came across this sign explaining why they are cutting many of the dead trees.
According to Douglas W. Tallamy in his book “Bringing Nature Home” (2007), Ash species host 150 species of native Lepidoptera larvae (moths and butterflies). Birds and other wildlife depend on these caterpillars for food. If the Emerald Ash Borer makes it to Delaware, erasing or seriously diminishing Ash in our local ecosystem, it could have a vast ecological and economic impact. Not only do plenty of insects eat the foliage, but Ash seeds are food for a variety of birds and small mammals.
This is an Ash tree that I found near Kennett Square, PA. It is mostly dead, with water sprouts coming out of the base. It was not attacked by Emerald Ash Borer, but had obvious insect damage from something different (see next photo). This is a typical scene in the areas where the Emerald Ash Borer infests trees to our west, mostly from western PA through Minnesota.
The Ash in the photo above from Kennett Square, PA had obvious insect damage under the bark, with tiny round exit holes from emerging insects. Emerald Ash Borer exit holes are shaped like a capital “D”, so it was some other kind of insect that infested this tree. The larval tunnels of the Emerald Ash Borer are similar in appearance, however.
What is being done now to control the pest? Mainly, scientists are looking at the natural enemies of this insect in Asia and have gotten as far as testing and receiving permits for release of several insects that attack the borer. They have released these insects in various Great Lakes states and are determining effectiveness. Check out this informational video about the project.
Have you seen one of these purple boxes hanging from a tree? This one is along Route 82 north of Ashland along Red Clay Creek. Researchers use this insect trap to determine the presence of the Emerald Ash Borer. So far, they haven’t found any in our area.
Unfortunately, the Emerald Ash Borer is headed towards Delaware. No one is sure when or if it will get here, but in Pennsylvania it has essentially infested the western half of the state, and new infestation areas spring up all the time.
Humans are helping the spread, and this insect is leapfrogging to new areas, mostly by people that move firewood or other woody debris or nursery stock containing the insect. In 2012 for example, it leapfrogged to Warrington, Bucks County, PA and was also confirmed in Connecticut, making it the 16th state to confirm infestation.
What can you do? Do not move firewood! Buy local and burn local. If you go on a camping trip to a quarantined area, do not bring your leftover firewood home, since you may bring the Emerald Ash Borer with you. For example, this website shows the quarantine area in Pennsylvania.
In Delaware, Green and White Ash are extremely common forest trees. One of the largest trees at the Bucktoe Creek Preserve, and one of my favorite individual trees is a humongous Ash along Red Clay Creek. Ash are a very common street tree as well, and have been planted in many of our neighborhoods and towns, and possibly in your yard. In the coming years, we may be hearing more about this pest locally and how you might be able to protect individual trees through spraying. Hopefully through science, we can find a solution soon. Signing off from Ashland Nature Center…
Here are some websites to learn more about the Emerald Ash Borer: