Here’s a bit of good news: The National Arboretum says (article here) it has developed a strain of hemlock tree that is resistant to the wooly adelgid, a sap-sucking pest that is decimating populations of the tree throughout the Eastern Seaboard. New Hampshire has the pest – I’ve seen it on trees around me – but we’re near the northern range and it’s not too bad yet.
One reason for the insect’s power to wipe out large stands of hemlocks is its ability to reproduce parthenogenetically, or without their eggs being fertilized. This means female hemlock woolly adelgids can reproduce without males, resulting in substantial annual population increases.
Hemlocks are sometimes overlooked in forestry because they’re not worth anything on the market – lousy lumber. But they’re really important for forest ecosystems because they create a lot of shade and lower temperatures. That’s particularly an issue with small streams; if you remove all the hemlocks the water gets much warmer and certain species, such as trout, fade.
The hybrid has been growing and being tested since 2000, including on test sites in Connecticut. A plant patent has been applied for and the arboretum is looking for a company to grow and sell it.
On the flip side: Emerald ash borer continues to expand in New Hampshire. It’s now found in the southwest corner of the state.