Bark beetles in pines

Trees affected

Jeffrey pine (Jeffrey pine beetle); lodgepole, limber, whitebark and western white pine (mountain pine beetle); pinyon (pinyon ips)

First sign

Reddish pitch tubes on the trunk

Later sign

Crown fades green to yellow to reddish-brown

Worst after

Severe or prolonged drought

Around Lake Tahoe and the Carson Range the main pine is Jeffrey pine, and its main beetle is the Jeffrey pine beetle. Mountain pine beetle and pinyon ips attack other pines in Nevada. We identify the problem and remove or prune affected trees. We do not spray or inject.

What to look for

• Large, reddish pitch tubes on the bark, which mark where beetles bored in
• Boring dust in the pitch tubes and bark crevices
• Holes and flaked bark where woodpeckers have fed on the beetles
• Needles fading evenly through the crown, from green to yellow to reddish-brown

The US Forest Service notes that pitch tubes can be found long before the crown fades, and that by the time the crown is reddish-brown the new beetles have likely already left the tree.

Why drought matters

Jeffrey pine beetle populations boom after severe or prolonged drought, and the trees die in groups. During an outbreak, any Jeffrey pine more than 4 inches in diameter at breast height can be attacked. In dry periods a tree may not have enough resin to push the beetles out.

What the state surveys show

Nevada's 2023 forest health report, based on Forest Service aerial surveys, mapped mountain pine beetle on 2,214 acres, down from 10,711 acres in 2022, and pinyon ips on 191 acres, down from 16,392. The report credits a wet winter that helped trees pitch out beetles. Beetle pressure rises and falls with the weather.

What an arborist checks

• Whether the pitch tubes show successful attacks
• How much of the crown has faded
• Which neighboring pines are at risk
• Where the tree would fall, and how to bring it down safely

When removal is the answer

A pine with a faded crown will not recover. Dead pines become brittle and dangerous to climb, so do not wait long. At Lake Tahoe, a dead tree that could fall on a house does not need a TRPA permit, but check with the agency or your fire district about any other tree. See removing dead pines after bark beetles.