Spring is when most creatures start to wake up from the cold of winter to begin their lifecycles once again. There is an invasive pest however, that has used the winter months to slowly feed on hemlock shoots and branches and develop into adults in the spring.
This invasive pest is the hemlock woolly adelgid, an aphid-like insect that sucks the nutrients from hemlock trees, slowly killing them over time.
During this feeding time, the adelgid secretes a white waxy coating that looks like a small, round, cottony mass. That makes it possible to identify infested trees in the spring. These woolly masses are attached at the base of hemlock needles and can be spread by wind, mammals, and birds; with birds being one of the primary ways HWA can move. Humans can also spread HWA through vehicles, trailers, and campers that come in contact with infested trees, then move to a different location.
Michigan has more than 170 million hemlock trees that we want to protect. They provide important habitat and winter cover for many wildlife species, add diversity across the landscape, help stabilize and protect dune and riparian systems, and provide shade to create a cooling influence on rivers, streams, and creeks.
HWA has been found so far in four West Michigan counties, and it’s important to keep it from spreading. You can do the following to help prevent the spread of the hemlock woolly adelgid.
- Consider placing bird feeders at least 100 feet away from hemlock trees, or take them down from April through June; or
- Treat your hemlock trees with insecticides to prevent HWA from being established or to destroy existing HWA.
Hemlock trees are generally dark green and have somewhat droopy, lacy-looking branches. Needles are flat and attached individually to the branch. There are two white stripes on the underside of the needle.
