Nature showing up in the wrong place can be ecologically devastating. In May of 2016, the little metallic green-colored pest known as the emerald ash borer was thought to inhabit just 25 counties. A year and a half later, it has been discovered in 42 of Missouri's 114 counties and the spread doesn't appear to be slowing down.
Nature showing up in the wrong place can be ecologically devastating, snuffing out the competition and generally taking over the hills, hollows, plains and aquatic habitats with superior survival skills. Such has been the case with multiflora rose, sericia lespideza, rock snot, zebra mussel and a few other choice ecologic pests. Not to be outdone, the emerald ash borer that feeds primarily on ash tree species is showing its voracity here in the Ozarks. In May of 2016, this little metallic green-colored pest was thought to inhabit just 25 counties. A year and a half later, it has been discovered in 42 of Missouri’s 114 counties and the spread doesn’t appear to be slowing down.
“We think it’s (EAB) been around in a lot of places a lot longer than we’ve known about it,” said Mike Fleischhauer, resource forester in Rolla with the Missouri Department of Conservation. ”Populations have just been booming all of a sudden.”
The beetle made its unwanted debut in 2002 in southeast Michigan, where it is thought to have arrived in wooden packing crates from Asia. Since that time, it has spread through the upper Midwest into Missouri and the Northeast. The beetle is attracted to volatile oils released from the green leaves of ash trees as well as odor compounds from ash tree bark.
EAB attacks all species of ash trees, and kills nearly every tree it infests. At approximately a half-inch long, the green adult beetle feeds on leaves and does very little damage to trees. However, in its larval stage, the insect kills ash trees by feeding on the water- and nutrient-conducting tissues just under the bark.
Fleischhauer says once ash trees are invaded, woodpeckers looking for young EAB larvae as a food source, will strip the bark off of the trees.
[The result] is something called “blonding”,” he explained. “You can see it from a long way.”
On ash trees, this feeding activity reveals a white inner bark that is highly noticeable. Ash trees with bark blonding may not have EAB, but it is certainly worth reporting these trees for a closer look by trained foresters, such as MDC’s Fleischhuer.
“We have noticed a pattern of spread,” he said. He said a Pulaski County landowner called him about a group of ash trees in an upland drainage (“not where you’d expect to find them”). “There was just a whole bunch right in that area and the blonding was everywhere,” he noted.“You could find it leading right to the river and follow it into Laclede and Camden Counties.”
“EAB is estimated to cost Missourians more than $180-million in tree treatments, removals, and replacements over the next 20 years,” said MDC Forest Entomologist Robbie Doerhoff. “If you have a healthy, high-value ash tree in your yard, it can be treated with insecticides that will protect it from EAB. However, these treatments can be expensive and must be applied every year or two to guarantee protection. For some ash trees, the best option is removal and replanting with a different species such as an oak native to Missouri.”
The speed of spread of EAB in the state might be associated with a critical mass phenomena—the more insects and the resulting damage, the more noticeable that damage can be. Fleischhauer also thinks the moderate winter we have had in the past, favor not only ticks and chiggers, but EAB. The spread has also been attributed to moving infested firewood from county to county.
“We say ‘try to burn it close to where you get it,’said Fleischhauer.”Don’t be cutting wood and hauling it to a different state to go camping. Same if you have a place in the country, cut wood and haul it into St. Louis—that’s a good vector to transport a lot of pests quickly.”
Ash is not a great firewood species, compared to high energy burning oak or hickory. “People who cut firewood will say, ‘I know what ash looks like,’ but we didn’t know EAB was around until 2002—what other things are we carrying around that we haven’t discovered yet?” reasoned Fleischhauer.
Ash trees have been cut for forest products such as pallet material and furniture. What is to become of those markets when large swaths of these trees are decimated?
“Something will take it place,” the forester says succinctly. “We’re very fortunate here—oak takes over rather easily, though he notes it is slower growing. Box elder and sycamore will fill in the gaps as well, though they don’t have much value for forest products.
“There’s no telling what the ultimate affect will be, if EMB takes all the ash out of the ecosystem,” he said.
MDC encourages Missourians to help prevent the spread of this destructive pest by learning to identify signs of EAB and reporting possible infestations in counties where EAB has not yet been confirmed. For more information on insecticide treatments for ash trees, consult the Emerald Ash Borer Management Guide for Missouri Homeowners at short.mdc.mo.gov/ZSq.
For a map of EAB’s spread across Missouri, detailed information on identification, and a guide on insecticide treatments, visit eab.missouri.edu. Report suspected EAB damage in new counties to a local MDC forester, call MDC’s Forest Pest Hotline at 866-716-9974, or email email@example.com.