The emerald ash borer is the bug to watch, the beetle on the move in the Midwest region of the country. Small enough to fit on the face of a penny, the EAB is sometimes mistaken for other beetles and insects that have similar shapes and colors.

Contractors and others should report possible EAB finds to local pest authorities. Experts will visit sites to confirm infestations.

The Problem: Emerald ash borer (EAB), Agrilus planipennis

Photo: Howard Russell, Michigan State University, www.forestryimages.org

This Asian beetle, discovered in 2002 in southeastern Michigan and Windsor, Ont., infests and kills North American ash species (Fraxinus sp.) including green, white, black and blue ash. Damage is caused by the larvae, which feed in tunnels (called galleries) just below the bark. The serpentine galleries disrupt water and nutrient transport, causing branches, and eventually the entire tree, to die. Adult beetles leave distinctive D-shaped exit holes in the outer bark of branches and the trunk. Adults are roughly 3/8 to 5/8 inch long with metallic green wing covers and a coppery red or purple abdomen. They may be present from late May through early September but are most common in June and July.

Meet the Imposters:

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Six-spotted tiger beetle
This native beetle is a common predator of insects in woodlands in the eastern U.S. Tiger beetles are ground dwelling and prefer open habitats along trails and roads. Adults are 1/2 inch long and usually iridescent green or blue.

Photo: David Cappaert, www.forestryimages.org

Two-lined chestnut borer
This native borer attacks stressed and declining oak trees. Adults are dark colored with two lines on the dorsal (back) side. Larval feeding beneath the bark disrupts the transport of water and nutrients and can kill infested branches and entire trees.

Robert A. Haack, USDA Forest Service, www.forestryimages.org

Caterpillar hunter
This large ground beetle is a predator of other insects. It is often found under rocks, leaves, and other debris, but it will climb trees to find prey. These native beetles prey on foliage feeding caterpillars in the forest, including gypsy moth caterpillars. The caterpillar hunter generally feeds at night and hides during the day. Adults are roughly 1 inch long and are present from May through November.

Photo: A. Steven Munson, USDA Forest Service, www.forestryimages.org

Bronze birch borer
This native beetle attacks stressed birch trees. Adults are similar to EAB adults but are dark-colored. Like EAB larvae, bronze birch borer larvae feed in the phloem just below the bark. Heavily attacked trees typically die from the top down. Emerging beetles leave D-shaped exit holes in the bark. Swollen ridges under the bark result from callus tissue that trees sometimes form over larval galleries.

Photo: John Weidhass, Virginia Polytechnic Institute and State University, www.forestryimages.org

Japanese beetle
This exotic beetle has been established in the northeastern region for several years. Adults feed on the foliage of more than 300 plant species, including many common hardwood trees. Trees may be defoliated by late summer but are rarely killed. Larvae are common pests in turf, where they feed on the roots of grasses. Adults are slightly less than 1/2 inch long.

David Cappaert, www.forestryimages.org

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Fish Creek in the San Bernardino National Forest is the home of Southern California?EUR??,,????'?????<Photo: Erik Skindrud

Source: Kimberly A. Rebek, Eric J. Rebek and Deborah G. McCullough, Dept. of Entomology and Dept. of Forestry, Michigan State University

Tree-Facts

94: The number of woody plant pests listed in the North Dakota Tree Handbook.
Source: North Dakota State University Extension Service

1876: Year the little leaf notcher ( Artipus floridanus ) was found in Florida. This species is the smallest of the weevils, measuring about 0.2 to 0.25 inches in length.
Source: University of Florida IFAS Extension