Another Invasive Insect Heading to Iowa


While Iowans are seeing the first ash trees cut down to slow the spread of the emerald ash borer, yet another invading insect is causing a stir as it could threaten our walnut trees.

Robin Pruisner, an entomologist with the Iowa Department of Agriculture, says the pest called the walnut twig beetle is being found in nearby states, but it hasn’t been found in Iowa — yet.

“Research is ongoing on how to protect walnut trees,” Pruisner says. “We just don’t have a lot of answers. This is even newer than the emerald ash borer at this point in time.”

The walnut twig beetle carries what’s known as “thousand canker disease,” which is deadly to black walnut trees. There’s been no way found to reverse the disease or to kill the beetle without also killing the trees.

For many years, the beetle was only found in states like Arizona, California and New Mexico. Now, the rice grain-sized pest is being found well beyond the southwest, in states as far away as Virginia and Pennsylvania — and closer to home in Ohio, Colorado and Tennessee.

Pruisner suspects the insects are moving such great distances because people are enabling them to hitch long rides.