Ips beetle, Ips spp.,

Fig. 81   Adult. Note: rear concave depression lined with spines	Fig. 82  Egg and larval galleries. Larval galleries radiate from the central nuptial chamber. No frass is present.	Fig. 83  Larvae brood in a lodgepole pine tree. Ips galleries tend to contain multiple generations.

Tree Species Attacked: The most critical attacks occur in pole-size to mature lodgepole pine, ponderosa pine, and western white pine.

Insect Description & Damage Symptoms: Adults are reddish-brown to black, often shiny, cylindrical, and about 3 to 6 mm long. An easily recognizable feature of the adult is a pronounced concave depression at its rear end, which is lined on each side with up to six tooth-like spines. The head is not visible when viewed from above.

Adults emerge and begin their attack from mid-May to early June. Pitch tubes are rarely formed or are very small, but fine yellow-red boring dust is usually found in bark crevices. Attack usually advances from the top downward on standing trees. A change in the foliage colour from dark to faded green is usually the first obvious symptom, but the best way to determine if a tree has been attacked by Ips is to remove a piece of bark and examine the tree for evidence of egg galleries. Ips egg gallery patterns consist of a central nuptial chamber from which two or more egg galleries radiate. Larval galleries extend at right angles to the egg galleries and often score the surface of the sapwood, a characteristic that causes some to call the Ips "engraver beetles". The galleries are free of boring dust and frass. As the tree or top portion of the tree dies, colour change continues to yellowish-red and then a dull brick red. Two to three generations of beetles may be produced per year; therefore, engraver beetle populations can expand rapidly.

Damage: Ips beetles usually only attack dead, dying, or damaged trees. They are also often found in the upper portions and on the south sides of trees attacked by the mountain pine beetle, and in conjunction with black-stain fungus. However, heavy populations can build up in windthrow and slash, which can pose a threat to healthy green trees. Ips damage often occurs at the edges of cut blocks.

Similar Damage: May be confused with mountain pine beetle or other secondary beetles. Ips beetles can be distinguished by the gallery patterns and the distinct shape of the adult.

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BC Ministry of Forests
Forest Practices Branch
P.O. Box 9513 Stn. Prov. Gov.
Victoria, BC
V8W 9C2

Section phone: (250) 387-8739
Section fax: (250) 387-2136

Last updated February 19, 2002