Origin: Native of eastern Asia
Impact: In infested areas, this beetle has killed hundreds of millions of ash trees and has led to major efforts by state and local officials to limit its spread through strict quarantines and fines for the movement of wood, especially firewood, out of infested areas. The emerald ash borer has now (2020) expanded info 35 states, including Texas, as well as 5 Canadian provinces. In Texas, it was discovered in traps deployed in northeastern Texas in 2016. Adult individuals have been found in Bowie, Cass and Marion Counties and infestations have been found in Denton, Harrison and Tarrant Counties (2020).
View More Pictures
History of Introduction:
The emerald ash borer (EAB) is native to eastern Asia, and was first recognized as a pest in the U.S. in the Detroit, Michigan area in 2002 (though it may have entered the U.S much earlier). It was most likely brought into the U.S. in shipping containers, packing materials, or ash wood pallets.
The EAB is only known to feed on ash trees (Fraxinus species), so similar species emerging from other types of trees are not likely to be this pest. Ash trees can be identified by their smooth, odd-pinnately compound leaves, with smooth or widely spaced teeth on the edges. Branches emerge in pairs, opposite one another on main stems. Ash trees produce clusters of individual winged seeds (samaras).
Emerald ash borer adults are small, about 1/2 inch long and 1/8 inch wide, and a uniformly metallic, emerald-green color. The body is cylindrical, with wing covers that taper to a point, similar to other beetles in the family Buprestidae (see soapberry borer). The dorsal surface of the abdomen is bright coppery-red. This may only be visible if the elytra and wings are raised. This is the only Agrilus species found in North America in which the dorsal surface of the abdomen bright metallic red. This may be the simplest diagnostic character for separating Emerald Ash Borer from all other Agrilus species in North America. The dorsum of the abdomen is normally black, green or blue on all other North American species of Agrilus.
Adult EABs emerge from early April to late May and June. Female lay 50 to 100 eggs individually in bark crevices of their host trees. The winter is spent in the larval stage inside their host trees, where they feed on the water- and nutrient-transporting outer wood rings, mostly just under the bark. Larva feed only on living trees and form serpentine galleries just under the bark. The galleries are packed tightly with sawdust-like frass. Once EAB infests a tree, it can be difficult to control. Larvae pupate in the spring and emerge when temperatures reach 450 to 550 degree days (using a base temperature of 5O°F). When adult borers emerge, they create a "D" shaped exit hole approximately 1/8 inch in diameter.
First symptoms of trees infested with emerald ash borers include a dying-back from the top of the tree, splitting bark, and sucker growth (lateral epicormic shoots) from the base of the tree. Emerald ash borers seem to prefer trees already weakened by pests or adverse environmental conditions. Extensive woodpecker damage can also provide a clue to EAB activity.
If you have spotted Agrilus planipennis (Emerald Ash Borer), use this report form to send an email to the appropriate authorities.