Bugs could pose problem for pines

A Pine butterfly on the needle of a ponderosa pine in Baker County. The butterfly, native to this area, is in the midst of one of its periodic population surges. Although the insect’s larvae can harm trees, their outbreaks are usually short-lived. (Baker City Herald/S. John Collins)

Yet.

The insects are Pine butterflies, which are native to the region, said Bob Parker, forester for Baker and Grant counties.

“I’ll probably have a better picture next year when the eggs hatch,” he said.

The butterflies deposit masses of eggs in pine trees, and when the caterpillars emerge they start munching needles.

“They can do a little bit (of damage) or a lot,” Parker said.

The butterfly can affect each of the three pine species common in this area: ponderosa, lodgepole and whitebark.

After doing some research, Parker found that the Pine butterfly has caused large-scale defoliation in Idaho, Montana and Washington. A 1922 outbreak near Payette Lake caused a 25 percent mortality rate in mature ponderosa pines across 27,000 acres of forest.

The key, Parker said, is to have healthy trees that can recover from an attack.

“If it’s a healthy tree, it can come back and be OK,” he said.

The sudden appearance of these butterflies reminds him of an outbreak of Pandora moths in Central Oregon in the 1990s.

“They had these big, huge caterpillars. The trees were defoliated right down to twigs,” he said. “There was not a needle left. It was like a fire went through.”

He said the caterpillars of Pine butterflies aren’t nearly as big (the Pandora caterpillars are 4 inches long). And, if the winter is cold enough, the eggs won’t survive.

“But our winters have been relatively mild in recent years so that’s not likely,” he said.

He said outbreaks are typically short-lived, with a rapid increase for a couple years and then a decline due to starvation or the predatory ichneumon wasp.

“Past epidemics in Idaho and elsewhere were sprayed with a variety of treatments but whether pesticides will be needed, or if natural controls will do the trick, will be a question for forest entomologists to resolve soon.

“Just make sure your trees are maintained and in a good, healthy condition. They can survive a lot of things,” he said.

More information about the Pine butterfly is available by calling Parker at 541-523-6418.