Missouri Department of Conservation

The emerald ash borer is a small insect that’s causing big problems for Missouri’s ash trees.

This non-native beetle (Agrilus planipennis), which is commonly known by the acronym EAB, attacks and kills all North American species of ash trees. It was first discovered in the U.S. in Michigan near Detroit in 2002 and first found in Missouri in Wayne County in 2008. Since then, it has spread across most of Missouri. EAB was first detected in Laclede County in 2016 and the Springfield area in 2018. The most recent first finds in southwest Missouri were in Barry, Barton, Jasper, Newton and McDonald Counties this spring (2023).

This beetle, which is approximately a half-inch in length, is benign in the adult portion of its life cycle. It is the larval stage of this insect that damages ash trees. Once hatched from their eggs, larva start feeding on the xylem tissue of the ash tree. The larva make an “S” pattern as they feed. Once enough of the xylem is damaged, water flow to that portion of the tree is prevented. This results in that portion of the tree dying. The insects first attack the top of the tree and work their way down over a few years and different generations of the insect. After enough of the tree’s xylem is damaged the tree finally dies.

Dead portions of the tree or the whole tree (depending on how far the damage has occurred) dry very quickly and become brittle. These trees become extremely dangerous to takedown. EAB-killed ash trees have been known to collapse under their own weight after standing dead for only two years.

Branches that die as a result of EAB infestation may start falling from trees almost immediately, making them a safety concern for all that go near that tree. Whole trees that are dead are extremely dangerous and great care should be made when removing these trees. There have been instances of whole trees collapsing on top of the sawyer after only being touched by a running chainsaw.

Anyone with a dead or dying ash tree that is presumed to have been damaged by EAB, should have that tree removed as soon as possible. While the tree is still partially alive and still green, it will be much safer to remove. Trees that are not in residential areas such as woodlands and not near something of value or along a trail or road can be left to fall on their own as the risk to people is much less. This will provide habitat for wildlife in the form of a dead tree snag.

If you have an ash in good to great condition, you may consider preventatively treating it for EAB. Depending on the size of the tree will determine if you may use homeowner available products or need an arborist with an Applicators license to do it for you. MDC has a publication outlining these options, EAB Management Guide for Missouri Homeowners, which is available at mdc.mo.gov.

Research has shown one way EAB spreads is by the transportation of firewood that contains the larvae. So, whether you cut firewood for personal heating purposes or to sell to others, try to keep the source of your firewood as localized as possible. Forestry experts suggest people don’t transport firewood more than 50 miles, but obviously, the smaller distance any firewood travels, the better the chances of not spreading this harmful pest.

Learn more at mdc.mo.gov.

Jon Skinner is a Community Forester for the Missouri Department of Conservation. Information about tree care is at mdc.mo.gov/trees-plants/tree-care.