Health
Purple boxes treed to provide insect early warning
The Montana Department of Agriculture gets a lot of questions this time of year about an insect trapping program designed to slow or halt the nationwide spread of emerald ash borers, said Cam Lay, state entomologist with the department. The big purple prisms are the largest traps the department’s Pest Management Bureau puts out, and are too high up in trees for their labels to be readable.
“They can be a bit of a pain to handle,” Lay said. “They’re big, and coated with sticky glue that the bugs get stuck in. It’s impossible to put them together and get them hung up without getting the glue all over you.”
The traps will stay up until the flight period for the adult beetles is over, usually in early September, and then will be taken down to see if any of the metallic green insects were caught. “They’re still pretty sticky even after all that time,” Lay said. “If they fall down, we want people to call us rather than trying to handle the traps themselves.”
The emerald ash borer is an invasive beetle from Asia that specializes in ash tree species. Larvae eat the layer of live tissue just under the bark that carries nutrients and water back and forth inside the tree. Ash trees are native to Montana and have also been planted for decades in shelter belts and along sidewalks. In Helena, for example, nearly three-fourths of street-side trees are ash.
“Imagine the city with 75 percent fewer trees,” Lay said. “That’s what we are trying to prevent.”
The emerald ash borer was likely imported in pallets or wooden packing material. It was initially discovered in Michigan in 2002, and has since spread throughout the Great Lakes states and northern Midwest. Populations have also been discovered in Tennessee, West Virginia, Iowa, New York, Minnesota, and Maryland.
The insects do not fly very far. The newfound pockets of infestation undoubtedly were caused by human activity, Lay said.
“Firewood is the number one way emerald ash borers spread to new areas,” he said. “Most of our outreach efforts are to tell people not to bring firewood into Montana. Buy it here, and burn it here.
“It’s not the only beetle that eats ash trees,” said Lay. “But it’s the one without any natural enemies and the one that’s most destructive. It could potentially wipe out every ash tree in Montana. The earlier we find it, the easier it will be to manage the problem to prevent additional damage.”