LEBANON, Mo. – A recent examination of several ash trees in rural Laclede County shows an unwanted tree pest is continuing its spread across Missouri.
Missouri Department of Conservation (MDC) foresters have confirmed that the emerald ash borer (EAB), an insect whose life cycle is fatal to ash trees, has been discovered in Laclede County. This destructive insect has now been found in 31 Missouri counties. The bulk of EAB findings have been in southeast Missouri, Kansas City and St. Louis. This recent find is the first evidence of this non-native insect in the southwest part of the state.
EAB is a small metallic green beetle native to Asia. The approximately half-inch long insect was first discovered in the U.S. in Michigan in 2002. Most likely, that initial introduction was the result of the insect being transported here in packing crates and pallets made of EAB-infested wood.
Its first appearance in Missouri was in 2008 in a public campground near Lake Wappapello. Infested firewood was likely to blame for this introduction.
EAB only attacks ash trees. The EAB life cycle takes one year to complete. Adult beetles emerge from ash trees, leaving behind small D-shaped holes. EAB females then lay eggs on the bark of ash trees in early summer. These eggs hatch into larvae that bore into the tree’s vascular layer – the zone that transports water and nutrients through the tree. The larvae feed on this vascular tissue, creating winding tunnels on the wood’s surface. Ash trees typically die from this feeding damage in three to four years.
This tree mortality comes with a price tag for humans. Ash trees were widely planted in cities and parks decades ago after Dutch elm disease killed large elms at these sites. Now cities and homeowners in some areas are facing the expense of either treating ash trees that are at risk for EAB infestation with insecticide or removing them. Ash comprises approximately three percent of the trees in Missouri’s forests, but can be as high as 40 percent of the urban trees in some cities.
Missourians can help slow the spread of EAB by not moving firewood long distances. A statewide EAB quarantine established in 2013 by the U.S. and Missouri Departments of Agriculture restricts the movement of ash trees, logs and hardwood firewood from Missouri into states not known to have EAB. While it is legal to move firewood within Missouri, officials recommend not moving it more than 50 miles from where it was cut to slow the spread of EAB and other invasive forest pests.
More information about EAB, including insecticide options for protecting ash trees from EAB, can be found at your nearest MDC office or at mdc.mo.gov.