Hemlock Woolly Adelgid
*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:
- Guidelines for homeowner treatments of hemlock trees infested with hemlock woolly adelgid - July 2017 - MSUE
- Hemlock Woolly Adelgid in Michigan - Recommendations for Landowners - September 2016
- Options for Protecting Hemlock Trees from Hemlock Woolly Adelgid - January 2017 - MSUE
- Insecticide Application Limits for Treating Hemlock Woolly Adelgid - November 2018
- Letter to Licensed Pesticide Application Businesses in Allegan, Kent, Muskegon, Oceana and Ottawa Counties
- Letter to Property Owners in Muskegon and Ottawa Counties
- Hemlock Woolly Adelgid Informational Meeting Presentation from 10-3-16 and 10-5-16
- VIDEO - Hemlock Woolly Adelgid - MSU Extension - Background/Damage, Life cycle, Identification, Hemlock and Its Importance
- West Michigan Hemlock Woolly Adelgid Taskforce website
- NEW! MSUE Hemlock Woolly Adelgid Bulletin (printable PDF)
- Michigan Departments of Agriculture & Rural Development and Natural Resources Hemlock Woolly Adelgid Forest Pest Alert (printable PDF)
- Small Format Hemlock Woolly Adelgid Forest Pest Alert (printable PDF)
What does Hemlock and Hemlock Woolly Adelgid Look Like?
- Hemlock Tree Identification
- Hemlock Woolly Adelgid Look Alikes
- USDA-Forest Service Hemlock Woolly Adelgid Pest Alert
- Hemlock Woolly Adelgid Interior Quarantine
- Hemlock Woolly Adelgid Exterior Quarantine
- Hemlock Woolly Adelgid Exterior Quarantine: List of Regulated Counties
- Michigan Plant Pest Quarantines
- Michigan Quarantine Summary for Licensees
Links of Interest
- USDA-FS-Forest Health Protection - Hemlock Woolly Adelgid: Publications and Other Information
- USDA-FS-Forest Health Protection - Hemlock Woolly Adelgid: Distribution Maps
- Dontmovefirewood.org - Hemlock Woolly Adelgid Gallery
- U.S. Fish & Wildlife Service - Hemlock Woolly Adelgid: Climate Change Invites Invasive Insect North