Forest and Wildlife Extension

Forest Health Notes

A Series for the Non-Industrial Private Forest Landowner

back to Forest Health Notes Table of Contents

Red Turpentine Beetle
(Dendroctonus valens)

Hosts: Ponderosa pine, lodgepole pine, western white pine, occasionally spruce and larch

Quick ID:

• Large reddish pitch tubes on trunk
  
• Only in lowermost portion of trunk
  
• Galleries short, irregular
  
• Galleries packed with frass
  
• Adult insect reddish brown, large

Field Identification

Tree: Large (up to 1 1/2"), globular pitch tubes at point of entry, full of frass (a mixture of sawdust and insect droppings) and reddish. Galleries of the insect are irregular and packed with frass, varying between 1/2 and 1" in width and up to several feet in length. Individual larvae galleries are not constructed; instead, a large cavity is formed. Galleries are usually found only in the bottom six feet of the trunk.

Insect: Adults are reddish-brown and may be 3/8" in length, the largest of the Dendroctonus bark beetles. Larvae are up to 1/2" in length, and feed together in a common brood chamber. Pupal chambers may be found at the base of the host tree.

May be confused with: Mountain pine beetle.

Life cycle: Attacks occur through the warm weather and peak in midsummer. Adult turpentine beetles bore through the outer bark and excavate short, irregular, longitudinal to cavelike galleries between the bark and the wood. Eggs are laid in groups packed with frass on the sides of the gallery. When the eggs hatch, the larvae remain together and excavate large cavities while feeding. Further development to pupae and adults takes place in the cavity or in short galleries along its margin. Larvae and adults overwinter in the tree. Generations per year varies with climate; in the coldest part of the range, one generation is produced every two years, while in the warmest areas, two to three generations may be produced in one year. This is not one of the most aggressive bark beetles and attacks do not become epidemic.

Predisposing factors: Red turpentine beetles commonly attack trees already weakened by injury, other bark beetle attacks, or disease. Freshly cut stumps, exposed roots and the lower trunk of declining trees are all attacked, as are "leave" trees after logging operations and fire survivors. It is commonly associated with attacks of Ips or mountain pine beetle, which are usually responsible for the actual death of the tree.

Impact: As this bark beetle does not become epidemic, losses are not as catastrophic as with the mountain or western pine beetles. Occasionally it kills trees that have been scorched by fire. The Forest Service puts it in a group with a number of other bark beetles for which losses in 1990 in Washington ran about 118.9 million cubic feet.

Management: Silvicultural activities designed to maintain vigorous, fast-growing stock will help as these trees are more resistant to bark beetle attack generally. Minimizing injury to "leave" trees during logging and silvicultural operations will keep the tree from being weakened. Pruning dead branches is fine, but pruning live branches opens a wound that may attract turpentine beetles. Bear in mind that root rot diseases often predispose the tree to bark beetle attack; search the roots and root collar for signs of infections. On high value trees near woodland homes or in campgrounds, chemical sprays may be used to prevent attacks. Lastly, salvage logging of beetle-killed trees is acceptable providing root rot is not present.

Note: Use pesticides with care. Apply them only to plants, animals, or sites listed on label. When mixing and applying pesticides, follow all label precautions to protect yourself and others around you. It is a violation of the law to disregard label directions. If pesticides are spilled on skin or clothing, remove clothing and wash skin thoroughly. Store pesticides in their original containers and keep them out of the reach of children, pets and livestock.

back to Forest Health Notes Table of Contents

About Forest Health Notes

Forest Health Notes were prepared by Donna Dekker-Robertson, Peter Griessmann, Dave Baumgartner, and Don Hanley, Washington State University Extension. The assistance of Robert L. Edmonds and Robert I. Gara, University of Washington College of Forest Resources, is gratefully acknowledged.

Insect or disease treatments should always be part of an overall forest management planning process. It's a good idea to have a forest management plan for your property. This tool will help you prevent problems and keep your forest healthy. For information on forest stewardship educational programs, contact your local WSU Extension office. For information on technical assistance and financial incentive programs, contact the Washington Department of Natural Resources. The Natural Resources Conservation Service will assist landowners in developing conservation plans.