Q. What are the signs and symptoms of the ips beetle (A.K.A. engraver beetle)?

A. Usually the first physical sign of an ips beetle infestation is brown dieback at the top of the tree as the beetles burrow into the bark and produce girdling tunnels. A yellowish- or reddish-brown boring dust accumulates in bark crevices at the entrance site. When the larvae complete development, the adults exit the tree, leaving small round holes peppering the bark. The beetles then move down to another part of the same tree or to neighboring trees.

Ips beetles are reddish-brown to black in color and are 1/8 to 3/8 inches long, with a pronounced cavity at the rear, lined with three to six pairs of tooth-like spines, depending on the species. The distinctive abdomen markings differ from other bark beetles.

Unlike the mountain pine beetle, ips attacks trees in stress due to injury, declining age, drought and other factors. However, if there is widespread infestation, ips beetles are a considerable threat to living trees. Two contributors to the spread of ips are freshly-cut infested wood not properly de-barked and disposed of and local storage of infested firewood.

Q. How can I protect my spruce from getting ips beetle?

A. The best defense is a healthy tree. To promote a vigorous tree, incorporate practices such as:
• Plant trees in proper landscape settings to allow optimal growing conditions as the tree matures.
• Adequate – but not excessive – water. In general, susceptible trees need monthly deep watering, year round.
• Prevent root injuries that can be caused by mechanical damage, compaction, or disease.
• When pruning or thinning your trees, remove debris from the vicinity of valuable trees.
• Never stack green or infested coniferous wood next to living coniferous trees.

Trees at risk include newly transplanted trees, trees suffering root injuries from construction, and those surrounded by large breeding populations of ips beetles. These trees may benefit from preventive insecticide applications on trunks and larger branches. Since ips overwinter, during high-risk conditions apply insecticides as soon as daytime temperatures consistently reach 50 to 60 degrees F in two treatments (early spring and summer).

There is no chemical treatment for trees or wood already infested by ips beetles. When taking out an infested tree, reduce threat to nearby trees by bark removal, chipping the wood into small pieces, covering piles with a double-layer of 6-mil thick clear plastic sealed around the edges with soil to heat the wood, or physical removal of infested material from the site to an area at least one mile from susceptible trees.

For more information see Fact Sheet #5.558 on “Ips Beetle.”

Gardening and Insect Fact Sheets are available on-line by clicking HERE.

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This page updated:  August 4, 2008