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It’s a bug’s life: bitter cold not enough to slow emerald ash borer

Local arborist and entomologist say recent cold temperatures not enough to kill invasive bug species.

DAVENPORT, Iowa -- Local arborist and entomologist say recent cold temperatures not enough to kill invasive bug species.

As the Davenport's city arborist, John Vance's job is to protect the trees. So part of his job means looking for trees infected by the Emerald Ash Borer. The beetles lays eggs, or larvae, in the cracks of bark on Ash trees. The larvae then burrow just beneath the bark surface, eating key nutrients the tree needs in order to survive.

The record-low temperatures in recent days are usually deadly for invasive bug species like the Emerald Ash Borer. However, many professionals -- like Vance -- said it's not cold enough. So he set out to find some himself.

"When I start scraping (any tree) I'll find one," Vance said. "But you can see it's not frozen, it's still soft."

Vance said it's not common for the larvae to become dormant during winter months, but that doesn't mean they're dead and gone.

"I like optimism but I'm optimistic that this isn't going to stop them," Vance said. "This whole park is infested. I mean you can look around - look at that tree there you can see all the flecking on the bark over there. They've been working that tree for a long time."

As an entomologist, Tierney Brosius is familiar with what bug species can and cannot handle. As she puts it -- she's a self proclaimed Bug Lady.

"I always talk about them with so much admiration but they actually do a lot of harm and destruction," Brosius said.

She said it is possible that the bitter cold cost the beetles 90% of their population. Still, that remaining 10% is far from gone.

"They are adapting to our cold temperatures," Brosius said. "So you have to remember that, that 10% that was leftover - they probably all had some sort of adaptation that allowed them, that was maybe a little different than ones around them, to survive and they will be the ones laying eggs and having future generations."

With each Emerald Ash Borer laying nearly 100 eggs or more, their population can rebound in just two years.

"It was definitely cold enough, I just don't think it was (cold enough) long enough," Vance said.

The Emerald Ash Borer has been confirmed in Illinois, Iowa and 34 other states.