SOUTH DAKOTA DEPARTMENT OF AGRICULTURE

NEWS RELEASE

For Immediate Release: March 14, 2013

Media Contact: Marcus Warnke, 605-394-2395

Pine Engraver Beetles A Concern In Urban And Rural Conifer Forests 

RAPID CITY, S.D. – Infestations of the pine engraver beetle (Ips pini) are now becoming more pronounced and are being mistaken for Mountain Pine Beetle (MPB) infestations in the Black Hills.

In rural areas and communities of the Black Hills, many landowners’ trees are being killed by bark beetles. Most people are familiar with the MPB problem in the Black Hills and across western North America but it is not the only bark beetle threatening the Black Hills.

Pine engraver beetles are smaller than MPB, and go through two to three life-cycles in a single year. Often the adults will over-winter in the duff, or upper layers of the soil, which makes cutting and chunking an ineffective management tool for engraver beetles.  

“The pine engraver beetles typically begin flying in late March or early April,” says Marcus Warnke, SDDA Service Forester. “These beetles will generally attack trees that are weakened, or stressed from other environmental factors, and can often be found infesting recently cut green slash.”

When trees are not overly stressed, it is likely the engraver beetles will only infest the limbs of cut or pruned trees. When their population numbers are great, they will infest and kill the tops of trees. With the current drought and mild winters experienced in South Dakota, there has been an increase in ponderosa pine trees killed by the pine engraver beetles in both ornamental and forest settings.

A tree infested with engraver beetles rarely produces the pitch tubes found on trees infested by MPB.  Instead it produces large amounts of boring dust, or frass, making infested trees difficult to identify. The frass is very fine, and usually rust-colored, and can be found within the bark crevasses and around the base of pine trees, or appear as piles of rust-colored dust on the stems of green branches in slash piles. The needles of trees infested with pine engraver beetle can fade from green to yellow in a matter of weeks.

In urban settings, it is important to maintain adequate soil moisture to ensure trees are not stressed.  Also, people should not transport wood potentially infested with beetles. Thinning of dense stands will help to reduce stress of the remaining trees and the stands’ susceptibility to MPB. Thinning, chipping and pruning create slash that can attract pine engraver beetles and should be avoided between March 15^th and August 1^st if possible. When sprayed earlier in the year and on the treetops, the same preventive sprays used to protect trees from MPB are also effective against the engraver beetles.

For more information regarding bark beetle infestations, visit http://sdda.sd.gov/conservation-forestry/, or contact SDDA Division of Resource Conservation and Forestry at 605-394-2395, or an Urban Forester in your community.

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