Battling Bark Beetle In Idaho With Pheromones That Say ‘No Vacancy’

May 15, 2018

Bark beetles are tiny insects that both thrive on – and contribute to – wildfires. Idaho forest managers are making use of a natural chemical the beetles produce to protect against further damage.

After two wildfires ripped through forests in north central Idaho in 2015, the Idaho Department of Lands received a Forest Service grant to minimize the long-term damage of invading bark beetles.

Bark beetles kill trees by burrowing into them, feeding off the interior bark and cutting off the flow of nutrients to the rest of the tree.

Tom Eckberg oversees the state program and says the tiny insects send out pheromones to get other beetles to overtake a douglas fir tree. They also send out another pheromone, known as MCH, which tells their fellow beetles to keep moving.

Credit Idaho Department of Lands

“Male beetles will send out the MCH signal to tell the beetles that this tree is full," says Eckberg. "Essentially it’s a ‘no vacancy’ signal. This tree is full and you need to go find your own.’ ”

Since 2015, forestry crews have stapled packets of synthetic MCH to douglas fir trees in forests around northern and eastern Idaho. The signal doesn’t kill the beetles, but rather keeps them from setting up shop in previously burned and susceptible areas.

“It costs about $50 an acre for the pheromone and then plus the cost of application. So it’s not inexpensive but when you’re protecting a resource often it does pay off economically.”

Eckberg says although overall bark beetles numbers have declined in recent years, the douglas fir beetle population is on the rise.

Find reporter Frankie Barnhill on Twitter @FABarnhill

Copyright 2018 Boise State Public Radio