emerald ash borer
Agrilus planipennis Fairmaire, 1888

Emerald ash borer (EAB) is native to Asia. It is known to be established in Michigan, Ontario, Ohio, Indiana, Illinois, and Maryland. EAB probably arrived in the United States on solid wood packing material from Asia. U.S. pathways include the movement of infested ash trees, limbs, firewood, logs, and untreated ash lumber. Hosts include all ash species; however, green ash, white ash, and black ash are more susceptible than Asian varieties. Females lay eggs 2 weeks after emergence. During this time, adults feed on the leaves, making them irregularly notched. Eggs are initially light-yellow, turning to brownishyellow before hatching. Eggs hatch in 1-2 weeks, and the tiny larvae bore through the bark and into the cambium layer. The creamy white larvae are 1 – 1 1/4 inches long with flat, broad, segmented bodies. Larvae feed in the cambium creating S-shaped, frass-packed tunnels. Adults begin emerging in mid-June leaving 0.1 – 0.2 inches "D" shaped emergence holes. It is a small, brassy-green, metallic woodboring beetle measuring 1/3 to 1/2 inches in length. Vertical splits in the bark are created by the tree forming callus tissue in response to larval feeding. The damage by the larvae causes general yellowing and thinning of the foliage followed by crown dieback and the eventual death of the tree. Basal sprouting and the presence of woodpeckers may indicate wood-boring beetle activity. After 1 to 2 years of infestation, the bark often falls off in pieces from damaged trees, exposing the insect galleries. The life cycle in Michigan takes between 1-2 years.

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