It was only a matter of time before Vermont joined New Hampshire, Connecticut, Massachusetts and New York as a host of the Emerald Ash Borer in the Northeast. This past week, the first evidence of an Emerald Ash Borer infestation was found in Orange, Vermont, bringing the number of states infected by this beetle to 32. The consensus is that the range of the Emerald Ash Borer has expanded rapidly due to the transportation of firewood from infested areas. On its own, the Emerald Ash Borer might spread one or two miles annually – far less than has been the case.
Other than seeing the Emerald Ash Borer itself (either the adult or the inner bark-eating larva) you can detect its presence by 1/8-inch-wide, D-shaped holes in ash bark and by S-shaped tunnels under the bark (see photo).
The insect does the most damage in its larval form, when it chews meandering tunnels through the inner bark of an otherwise healthy tree, depriving the tree over time of the means to transport water and nutrients. The Emerald Ash Borer affects all species of ash and once infected, trees usually die within a year or two.
The ash is the third important North American tree to succumb to blight over the last century, following the American Chestnut, and the American Elm. About one percent of ash populations survive infestations; these trees could indicate genetic tolerance which could hold hope for the future. (Photos: public domain)
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As you may have heard, there could be a plus side to the sub-zero temperatures we’re experiencing this winter – the cold weather may well decrease the number of invasive pests we have. For example, the Hemlock Woolly Adelgid (the aphid-like introduced insect decimating the Eastern Hemlock population) succumbs at 4 or 5 degrees F. However, other insects aren’t phased by the cold until it dips way below zero. At -20 F., roughly half of the Emerald Ash Borer larvae (an invasive beetle that is highly destructive to ash trees) overwintering in trees will die. Once the temperature reaches -30 F., there’s a 90 percent mortality rate. Bed bugs face instant death at -22 degrees F., but it takes 24 hours to kill them at -11 degrees F. and 72 hours to kill them at 0 degrees F. Unfortunately, once an invasive insect establishes itself, even if its numbers go way down for whatever reason, it usually rebounds in several years’ time. Some invertebrates are not affected by the cold temperatures. The Black-legged (Deer) Ticks that reside on moose, deer, mice, birds and other hosts can withstand sub-zero temperatures as they have the warmth of their hosts’ bodies to keep them warm. In order for ticks to succumb to the cold, the frigid air has to last until May, when the fertilized female ticks fall off their hosts to lay their eggs.
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.