Stinkbugs enjoy an invasive tree - and hitchhiking

STAUNTON, Va. (AP) - Area farmers should be worried about invasive stink bugs destroying crops and fruit, but they don't have to wait until next summer to address the problem, experts say.

The thumbnail-sized insects, originally from Japan, Korea and China, like an invasive tree - sometimes called a stinktree or Tree of Heaven - and farmers seeking to get rid of the smelly bugs should think about getting rid of the not-so-heavenly smelling tree.

Stink bugs, first identified in the United States in Allentown, Pa., in 2001, heavily infested some Shenandoah Valley soybean crops for the first time this past summer, according to a Virginia Tech report.

Augusta County, in particular, was one of three counties in the Valley found to have the shield-shaped bugs in high enough concentrations to be considered a significant economic threat, along with Frederick and Clarke counties.

"The risk for economic damage is there," said Dr. Ames Herbert, an extension entomologist with Virginia Tech.

"But," he cautioned, "There are certainly fields in (Augusta) County that had no (stink) bugs."

The bugs have spread to at least 30 states and have gone as far as California, but they don't spread rapidly on their own, Herbert said. They catch rides on vehicles.

"They call it the interstate bug," Herbert said. "Most of the infestation has been in the mid-Atlantic states, including parts of Virginia, but they've reported some pretty high numbers in Washington and Oregon."
Once established, a population can balloon quickly because of a lack of natural predators.

"In Maryland they had low numbers in 2009, and then in 2010 they found large infestations on field edges," Herbert said. "The same pattern has occurred for us.

"In 2010 we found a few, and then this summer we found several fields with very high numbers."

This particularly variety of stink bug is called the brown marmorated stink bug and can be distinguished from its native cousins by white color bands along the antennae and the outer part of the thorax. Also unlike native stink bugs, they overwinter inside, invading houses and office buildings in the fall, and emerge in the spring ready to devour just about any fruit or vegetable they can find.

"They like a hell of a lot of things," Herbert said. "It has an extremely large variety of hosts - corn, tomatoes, peppers, peaches, nuts, you name it. Even grain. We are concerned about what it will do when it's introduced to our wheat crop."

Farmers worried about the pest are not helpless, however, and they won't even have to wait until next summer to start working on eradicating the pests. They can start with one of their favorite habitats right now.

"Heavy infestations seem to be associated with fields with wooded borders, especially if there are concentrations of the invasive weed Tree of Heaven," Herbert said. "Both are native to China and the (stink bug) seems to be strongly attracted to that host, especially when the trees are putting out their seed clusters. It's like a happy reunion."

The highest concentrations of the stink bugs have been found where the invasive plant is also found in high numbers, Herbert noted.

The Tree of Heaven, scientific name Ailanthus altissima, is also known as China-sumac, Paradise Tree, varnishtree and stinktree, was introduced to the United States around 1748 by a Pennsylvania gardener and has spread throughout the states.

For a time, the up to 80-foot tree was even sold commercially, and it is now prevalent in 42 states and is the most common non-native tree in the Shenandoah National Park, according to the park service.

"I have not seen any (area) farms that don't have that tree on it," Rockingham County agriculture extension agent Matt Yancey said. "It's gotten out of hand and become very problematic as an invasive."

It produces a toxin in its leaves and bark that inhibits the growth of other plants, and grows and spreads rapidly, Yancey said. It can survive in the harshest of conditions and is probably best known as the species of tree referenced in Betty Smith's famous novel, "A Tree Grows in Brooklyn."

"It's displaced a huge amount of our native trees," he said. "Most farmers I don't think are aware that control of the tree is possible over winter, and with the stink bugs (using it as a host) that's just another great reason to kill this tree."

While the tree's best use is as firewood, Yancey said, it resprouts vigorously when cut.

"Cutting is not a good idea if you don't immediately apply an herbicide to the base or stem," he said.

Herbicides containing triclopyr are effective if used immediately after cutting a tree down, and they are available for general use at many area retailers.

"You can do it in the dead of winter," Yancey said. "As long as the ground is not frozen and there's no snow on the ground."

The tree is identifiable during the winter months by large, thumb-nail size scars on the branches left from fallen leaves. It also, like the bug, is armed with a pungent aroma to ward off predators.

"People say it's like a rancid peanut butter or cashew smell," Yancey said. "I don't know what rancid peanut butter smells like, but (the tree) is pretty nasty."

Taking the trees out now, might help ward off the stink bugs later, Yancey and Herbert agreed.

"It's not an uncontrollable problem," Herbert said. "Taking out the Tree of Heaven will certainly help.

"There's no doubt (the stink bugs) like that tree."