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. |
