Emerald Ash Borer: Small Bug, Big Utility Threat

September 2006

City and utility officials in Iowa are urged to help in the early detection of a possibly devastating pest infestation that could be on the horizon.

The emerald ash borer is an extremely dangerous and destructive exotic pest that has been found in Michigan, Ohio, Illinois, Indiana and Ontario, Canada. The emerald ash borer is a small beetle that attacks ash trees, and can be lethal to tree population. First discovered in Michigan in 2002, the pest has killed more than 15 million ash trees in that state alone. The cost of removing diseased trees can be potentially devastating to affected municipalities and/or property owners.

Some officials predict that it may only be a matter of time until the emerald ash borer arrives in Iowa, and that an infestation could be even more devastating than the outbreak of Dutch Elm Disease, which hit Iowa hard in the 1960s. Iowa State University is now in its third year as part of a collaborative effort to watch for the spread of the emerald ash borer. Extensive surveys and scientific techniques have been employed in Iowa in 2005 and 2006, and to date, no emerald ash borers have been detected – however, officials are urging cities and municipal utilities to teach their tree trimmers and electric line workers to become aware of the signs of emerald ash borer infestation and act as key components in an early-warning system.

Utility workers and managers are urged to follow these steps:

• Know the signs and symptoms of emerald ash borer activity.
  • Emerald ash borer adults are dark, metallic and emerald green beetles, measuring one-half inch long and one-sixteenth of an inch wide.
  • White larvae feed under the bark of ash trees and produce “S-shaped” tunnels.
  • Adults leave “D-shaped” emergence holes on ash tree trunks. Other borers leave round or oval holes.
  • Symptomatic trees display thinning and dieback of the upper one-third of the crown. Root and stem suckers (“water sprouts” or epicormic shoots) are produced by affected ash trees directly below borer activity.
  • A photographic gallery for the emerald ash borer can be found at www.insectimages.org
• Obtain an emerald ash borer poster and post it on a bulletin board in your workplace. Posters as well as wallet-size cards are available through Iowa Department of Natural Resources – Forestry Bureau and Iowa Department of Agriculture & Land Stewardship – State Entomologist Office.
• Bookmark your Web browser and keep up with current research and survey findings in MI, IN and OH: www.emeraldashborer.info
• Report suspected sightings of emerald ash borer adults or symptomatic trees to the State Entomologist’s office, any local Iowa State University Extension office, or any district forester with the Iowa Department of Natural Resources. Remember, there are native insect borers that colonize declining or dying ash trees and are not of special concern. There are also several insects that can be mistaken for the emerald ash borer. Check out: www.emeraldashborer.info/files/e-2939.pdf for more information.

In addition to recognizing the signs of the emerald ash borer, city and utility officials are urged to make advance plans now for handling an infestation – for example, if ash trees in your community would need to be removed, would the city/utility or the property owner be responsible for the cost? If it is determined the city/utility would be responsible, policy should be implemented for covering the possible financial ramifications.

The subject of the Emerald Ash Borer will be covered as part of the IAMU Tree Pruning & Maintenance Workshops being held around the state in September.