While we've all been shivering from the recent and multiple below-zero temperatures, certain invasive insect species have suffered the blow as well. As an arborist involved in the Plant Health Care (PHC) program at ArborTech, I know the deep freeze is good news, even as I lament that my 20 year-old Toyota pickup truck refuses to start on such bitter cold mornings.
Take for example the Hemlock Wooly adelgid, commonly referred to as HWA, an introduced pest originally from Japan that came to the United States in the 1950's.
Much has been written about the HWA and it's one of the most common insects we treat in the tree service industry. A tiny, aphid-like insect, the HWA pierces the base of the needles and sucks out the much-needed supply of water and nutrients. A heavy population of these insects will severely weaken and eventually kill its host plants.
With no natural predators in the U.S, the HWA population has been able to gain destructive footing. Luckily, extreme cold has the potential to knock back the populations of invasive insects. Typically, PHC practitioners here in Massachusetts have counted on a truly cold winter every few years as a management tool. However, as global temperatures are rising, and we experience milder and milder winters, HWA populations are not only rising here in MA, they are moving further North into the upper regions of New England.
Luckily, there are a number of treatments that are available and effective at managing these insects. If you see the tell tale white cottony masses on your Hemlock trees, or a significantly thinning crown, don't assume the worst. Call ArborTech for a comprehensive site visit and review of the treatment options. If caught and treated early enough, most Hemlocks recover nicely and will be around for years to come.
Perhaps we should try and appreciate the severe cold temperatures we are experiencing for the good they are doing. At least for our Hemlocks!