Environment
4:18 pm
Tue January 21, 2014

State Entomologist: Cold Not Enough To Stop Invasive Bugs

Wooly Hemlock Adelgid was discovered to be killing trees in the state in 2000.
Wooly Hemlock Adelgid was discovered to be killing trees in the state in 2000.
Credit BlueRidgeKitties / Flickr CC

While frigid temperatures don’t feel particularly great, they do play an important role in the state’s ecosystem.

One way that cold temperatures can be helpful is by beating back the wave of invasive insects that have laid siege to the state’s forests, but State Entomologist Piera Siegert tells NHPR’s Brady Carlson that the some of the recent headlines about the impact of this cold on invasive bugs over-state the case in the Granite state.

Siegert says Red Pine Scale and Hemlock Wooly Adelgid are both more exposed to cold than the Emerald Ash Borer, but all three bugs are adapted to deal with the cold. The Ash Borer in particular is remarkably cold hearty. Several recent media stories have stated that this beetle would be killed by cold of -30 degrees Farenheit, but Siegert says it has to be that cold "below the bark." In other words, there’s no guarantee that this cold will cause populations to decline.

“What really impacts the insects is going to be extended very cold temperatures, or warmups in February where the temperature comes up to a spring-like temperature and then goes through a rapid decline again,” she explains. Even if the populations do decline, Siegert says these bugs have an extremely “high reproductive potential” and would bounce back quickly.

One area where there could be some hope is with ticks. Siegert notes “with warmer winters we see more transmission of Lyme and more people picking up ticks even in the winter months” but she hesitates to make any predictions on if a cold winter will help New Hampshire’s declining moose populations.

“I think hindsight is always 20/20” says Siegert. New Hampshire Fish and Game and the University of New Hampshire are currently working on a mortality and productivity study in hopes of narrowing down the cause of moose deaths in the state.

Even though this cold snap might not be hugely consequential for the populations of invasive species, there’s no rest for a weary entomologist. Siegert says cold weather is the perfect time to look for trees damaged by Emerald Ash Borer.