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Thursday, Apr. 30th 2015

Emerald Ash Borer Adults Emerging Soon

Adults of the emerald ash borer (EAB) will start emerging about the time that black locust blooms and then be around through July. Black locust flowers are just starting to open in Columbia as of April 28. EAB adults are metallic green, bullet-shaped and about a half-inch long. To distinguish EAB from other green insects and view infested tree symptoms, refer to photos at

Where EAB infestations exist, emergence is expected to start around May 1 in southern Missouri, during the first week of May across the middle of the state, and in the second week of May in northern Missouri.

If you think you’ve found an EAB infestation in a county where it has not yet been detected, please report it. First, consult the map of known EAB positive counties. Reports can be submitted by toll-free phone (866-716-9974) or online at

If you live in a county where EAB has been detected, and you have ash trees that you are considering protecting with a systemic insecticide, the time to do that is either now or coming soon. Use of insecticides for EAB is recommended only in the same county or within 15 miles of where EAB has been detected (see map). Consult the new “Emerald Ash Borer Management Guide for Missouri Homeowners” to determine if your ash trees should be treated, when to treat, and what treatment options are available. Do-it-yourself insecticide treatments should be applied in mid to late April. Treatments that are applied by professional arborists through injection or spray on tree trunks should be applied after leaves have fully emerged on ash trees in late April to early May.

D-shaped exit hole

Emerald ash borer adults leave D-shaped exit holes about 1/8-inch wide in ash bark. MDC photo


Forest Health Program
Missouri Department of Conservation
To contact your local forester, see the local contact box at

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University of Missouri Extension Master Gardener Program