Emerald ash borer (EAB), Agrilus planipennis Fairmaire, (Coleoptera:Buprestidae) is a serious pest of all north American ash (Fraxinus spp.) white fringe tree (Chiananthus virginicus), and European Olive (Olea europaea) of all sizes. This pest is a small beetle (0.25-0.50 inches in length, 0.06 inches wide) with a bright metallic green color and coppery-red abdominal segments under the wings. They have long, narrow bodies that are rounded on the bottom and flat on the top. The life cycle of EAB includes eggs, larvae, pupa and adult stages. The larvae are 1-1.25 inches long, flattened, translucent pale-yellow color with a wide tan head, and 10 abdominal segments that are bell-shaped creating a serrated look. There are five larval instars of EAB.
Emerald ash borers are phloem and cambium-feeding insects. Minor damage is done by adult EAB which feeds on ash foliage, leaving irregularly shaped leaf margins. Larval stages cause significant damage by building galleries below bark in the phloem and cambium layers (producing new wood and conductive tissues). Larval feeding injury cause tree girdling, disrupting the transport of water and nutrients leading to the tree's death. Infested ash trees show symptoms including vertical bark splitting, serpentine (s-shaped) galleries behind outer bark, D-shaped exit holes from adult beetles (1/8 inch wide on the bark surface), canopy thinning, crown/branch dieback, epicormic shoots (suckers) from the base/lower trunk/branches and increased activity of woodpeckers. Larvae can survive in greenwood, firewood, and logs when the bark is attached, capable of spreading EAB from one place to another.
The emerald ash borer (EAB), native to East Asia, was first detected in Michigan, U.S., in 2002. In Texas, EAB was identified in Harrison County in 2016 and has since spread to 27 additional counties as of July 2024, with 11 new infestations in just one year. This invasive pest threatens North America's hardwood forests and nursery stock, killing unprotected ash trees, causing substantial aesthetic, ecological, and economic damage to urban forests. Human-assisted spread of EAB in Texas has been accelerated by movement of infested nursery ash trees, logs, landscape waste, and firewood, has accelerated EAB movement in Texas. These activities have played a significant role in the rapid spread of this invasive pest across the state. According to Texas A&M Forest Service, the management of EAB (treatment, removal of dead trees, processing debris, and replacement of trees) would cost more than $29 billion over the next 20 years in Texas. Chemical treatments, such as drenching or foliar applications, are currently the only effective method to protect ash trees infested by emerald ash borer (EAB). These treatments are most effective for trees with less than 30% canopy decline and for susceptible trees within a 30-mile radius of known EAB infestations.
Figure 1. Adult Emerald ash borer (EAB). Photo courtesy, Randy King
Figure 2. Emarald ash borer-infested ash trees with more than 50% canopy loss. Photo courtesy Daniel Herms, The Ohio State University, Bugwood.org.
Questions?
Please contact Rafia Khan Assistant Professor Extension Entomologist
- Email:
- rafia.khan@agnet.tamu.edu
- Phone:
- (903) -834- 6191
