Learning how to spot the hemlock woolly adelgid is the first step in protecting your trees.
The hemlock woolly adelgid (HWA) is a true bug that poses a serious threat to eastern hemlock, a common tree species in Maine. Native to East Asia, the HWA has been in North America for decades. However, in Maine, the first natural infestation wasn’t discovered until 2003 in Kittery and York forests. Unfortunately, the HWA appears to be spreading northward.
The Maine Forest Service is examining hemlocks near infested areas, hoping to catch the HWA before it becomes entrenched. However, they can only examine so many trees and are urging land owners to also be on the lookout.
The first step is to determine if you have hemlock on your property. This evergreen tree
is found throughout the state, especially on moist, cool sites. Unlike many trees, hemlock can grow well in full-shade or full-sun. It is often used as a landscape tree, and with proper pruning can create a dense hedge for use a windbreak or road screen.
Check out this Quick Key to Identifying Hemlock from the Maine Forest Service to learn more.
Once you’ve confirmed that you have hemlock on you’re land, you should examine your trees for HWA. Things to look for:
- Immobile, white woolly masses at the base of needles on undersides of hemlock twigs
- Trees that have been impacted for years will also display off-color needles, often with a grayish-cast; thinning crowns, premature needle loss.
Eggs are present in late March. This is when the wool is fluffiest, so we’re coming up on a great time to check for HWA.
HWA feeds on sap and in return probably injects a toxin, causing tree tissue to dry and eventually die.
Hemlock is an important resource. It is often found near water and protects against erosion while at the same time acting as a temperature buffer, protecting aquatic life such as brook trout. It also provides good winter shelter for deer and is food for many animals and birds.
Because of the many benefits provided by hemlock trees, we should do everything we can to protect them. The most common HWA management practices include removing infected branches, chemical controls, and predator beetles (yes, you read that right). This is a great fact sheet if you’re looking to become a real hemlock woolly adelgid expert.
Once again, thanks for reading.-Cam Gould Gould and Son Tree Service