Emerald Ash Borer
Agrilus Planipennis

The emerald ash borer (Agrilus planipennis or Agrilus marcopoli) is a shiny green beetle native to Asia. Since its accidental introduction into the United States, it has spread to seven states and adjacent parts of Canada and is considered an invasive species. It has killed at least 25 million ash trees so far and threatens to kill most of the ash trees throughout North America.

Identification:

The average length for an adult emerald ash borer is 20 mm (3/4 in) long and 4 mm (1/6 in) wide. The larvae are approximately 1 mm in diameter and 15 mm (.6 in) long, and are a creamy white color. The eggs turn to a yellow brown color prior to hatching.[2] Adults lay eggs in crevasses in the bark. Larvae burrow into the bark after hatching and consume the cambium and phloem, effectively girdling the tree and causing death within two years. The average emerging season for the emerald ash borer is early spring to late summer. Females lay around 75 eggs, but up to 300 from early May to mid-July. The borer's life cycle is estimated to be one year in southern Michigan but may be up to two years in colder regions.

Injury:

Evidence of the emerald ash borer sometimes takes up to a year to recognize. Some signs that the emerald ash borer has infested a tree are D–shaped holes in the bark of the trunk or branches and shoots growing from the base of the tree. The beetle kills trees because the feeding larvae damage both the phloem (responsible for nutrient transport throughout the tree) and xylem (responsible for take-up of water and nutrients) tissues of the tree. The beetle effectively strangles the tree. A tell-tale sign of infestation is new shoots sprouting from the bottom of the tree. As long as the beetle does not eat the bark at the very base of the tree, the small shoots at the bottom can still get nutrients. Surprisingly, even after the larger tree is cut down, some of these shoots may keep on growing.

Biology and History:

The natural range of the emerald ash borer is eastern Russia, northern China, Japan, and Korea. It was suspected to be accidentally imported to North America from China in the 1990s and has since destroyed more than six million ash trees in southeastern Michigan. It was discovered in June 2002 in Canton, Michigan. It has since been found in a few other parts of the United States and Canada. Ohio and Ontario have experienced emerald ash borer migration from Michigan, while Maryland and Virginia received shipments of contaminated trees from a Michigan nursery. The emerald ash borer was confirmed in Indiana in April 2004 and West Virginia in October 2007.