by Wizzie Brown
Emerald ash borer, often referred to as EAB, is an exotic pest from Asia. This beetle is a serious threat to ash trees. Emerald ash borer was accidentally introduced into the United States and was found in Michigan in 2002. It has now spread to 33 states, including Texas. In May of 2016, four beetles were found in a trap located in NE Texas (Harrison County). In 2018, the beetles were confirmed in two new counties, Marion and Cass counties.
Adult females lay eggs on the bark of ash trees. Once eggs hatch, larvae bore into trees under the bark and cut off the water and nutrient conducting vessels. Larvae are creamy white, legless with a flattened body. Larvae are 1- 1 ½ inches in length when fully developed.
As an adult, emerald ash beetles are elongated and cylindrical, somewhat shaped like a bullet. Most notably, these beetles are bright, metallic green with reddish hues. Adults are small, about 1/2 inch in size. If the wings are removed or lifted, the upper side of the abdomen is bright coppery-red which can help differentiate this beetle from closely related species in Texas. Please note that there can be varying coloration—more blue or reddish instead of green.
Infested trees show canopy die back in the top one third of the canopy moving downward until the tree is bare. Epicormic shoots (leafy shoots coming off the trunk of the tree) may also be seen. Vertical fissures may appear on the bark and galleries may be seen through openings. If bark is peeled off, serpentine galleries packed with frass may be seen. Adult beetles produce a D-shaped exit hole (1/8 inch diameter). Woodpeckers may cause damage to tees infested with EAB. Look for flaking bark and uneven holes caused by woodpeckers feeding on larvae and pupae.
If EAB activity is confirmed within an area, it is recommended that a systemic insecticide treatment is given to ash trees of high value. If more than 50% of an infested ash tree crown remains, then treatment with a systemic insecticide may slow the attack. If less than 50% of an infested ash tree crown remains, the tree should be removed.
For more information on emerald ash borer within Texas see the following site https://tfsweb.tamu.edu/eab/
For more information or help with identification, contact Wizzie Brown, Texas A&M AgriLife Extension Service Program Specialist at 512.854.9600. Check out my blog at http://www.urban-ipm.blogspot.com
This work is supported by Crops Protection and Pest Management Competitive Grants Program [grant no. 2017-70006-27188 /project accession no. 1013905] from the USDA National Institute of Food and Agriculture
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