The emerald ash borer beetle Agrilus planipennis is an invasive insect from Asia. It was first discovered in North American in the Detroit, Michigan and Windsor, Ontario areas in 2002. It has since spread to 15 states in the US and in the surrounding areas of Ontario via transport of firewood and infested nursery stock.
Emerald Ash Borer (adults) and tree damage from larvae.
Photo source: US Forest Service, David Cappaert, photographer.
The EAB beetle is about 10 mm long by 4 mm wide. The adults lay eggs in the crevices of ash tree bark in late May to mid-June. The eggs hatch and the larvae bore under the bark and consumes the cambium of the trees while going through several larval stages. Their random boring pattern cuts across the xylem and phloem of the cambium layer, thus cutting off the transport of water and nutrients which kills the trees. The larva overwinter and then pupate in the spring. Adults emerge from May to July from D-shaped exit holes, with peak emergence in mid-June. The life cycle of the EAB is usually one year, but can be two years in colder climates.
For more information, visit the emerald ash borer information website.