Department of Natural Resources
*Detected in Michigan*
Elizabeth Willhite, USDA Forest Service, Bugwood.org
CAES, Bugwood.org - Hemlock woolly adelgid up-close
Mark McClure, Connecticut Agricultural Experiment Station - Hemlock woolly adelgid damage
Why we care: These tiny insects secrete white wax as they feed on sap from hemlock shoots and branches. Hemlock woolly adelgid (HWA) feeding can kill needles, shoots and branches. Over time, growth slows as trees become less vigorous and trees may take on a grayish-green appearance. Infested hemlocks, especially large, old trees, are often killed when other stress factors, such as drought, affect trees.
What is at risk? More than 100 million mature hemlocks grow in Michigan. Hemlocks provide important habitat and winter cover for many wildlife species.
The threat: HWA populations are common in many eastern states, including Pennsylvania. Eggs and very young adelgids can be carried by birds and can be moved on hemlock nursery trees, logs or firewood.
What could happen in Michigan? Much of the state's hemlock resource is relatively old and very vulnerable to HWA. If this pest becomes established, most of these trees will be killed.
Allegan, Muskegon, Oceana, and Ottawa Counties Hemlock Woolly Adelgid Information:
What does Hemlock and Hemlock Woolly Adelgid Look Like?
Links of Interest