| By Elisa Campbell
Click on the pictures to enlarge them.
Dying walnuts trees. |
Indicating an exit hole of the Walnut Twig Beetle in a walnut trunk |
An attempt to catch a larva of the Walnut Twig Beetle |
Showing exit holes in a walnut branch by expert Whitney Cranshaw. |
In the Fall
2011 issue of the Sierra, I wrote an article about
accidentally-introduced insect pests of our trees, especially the Asian
Longhorned Beetle (ALB) and the Emerald Ash Borer (EAB). Since that
article was written, more ALBs have been found in Shrewsbury, so the
quarantine area has been expanded. On the other hand, fortunately, the
purple traps hanging in trees throughout western Massachusetts did not
catch any EABs, indicating those ravenous insects have probably not yet
moved into Massachusetts from nearby New York state. Scientists are
studying several kinds of wasps from the native habitat of EAB to try to
find a predator that can be introduced safely; there are some promising
candidates, but so far each wasp costs between $5 and $7 dollars! So
help is on the way, we hope – but it won’t be here quickly.
Another pest For the second year in a row, I attended a conference on
forest pests – “The Continental Dialogue on Non-Native Forest Insects
and Diseases. ” Last year the conference was at Brandeis and the field
trip was to Worcester to learn about ALB. This year we met in Boulder,
Colorado, and the field trip concentrated on the Thousand Cankers
disease (TCD), which kills walnut trees. The non-native fungus is
carried by the Walnut Twig Beetle, which is native in the southwestern
US. TCD is another non-native killer of forest trees that is too
widespread to eliminate.
It is not known to what extent climate change will help the beetle
expand its range into the northeast, but it’s not far away: in August,
TCD was confirmed in Pennsylvania. As usual, the main way it spreads is
by people moving wood; given the value of walnut for fine-quality
furniture etc., the danger in this case is less from keeping and moving
logs for firewood than for woodworking. Don’t do it!
Bat Update
On a related subject, scientists now believe that White Nose
Syndrome, which has killed over one million bats throughout the
northeast, is a fungus accidentally introduced from Europe.
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