Dendroctonus ponderosae Hopkins

From: Field Guide to Diseases and Insect Pests of Idaho and Montana Forests, USDA Forest Service Northern Region, Publication Number R1-89-54

Hosts. – All native and introduced species of pines.

Distribution. – Wherever host species are found in Idaho and Montana.

Damage. – Both adults and larvae feed in phloem layer of inner bark. Sapwood may be lightly scored. Feeding girdles the tree. Tree is inoculated with blue stain fungi clogging water transport system. Usually trees are killed, but some may be strip attacked. Trees less than 5 inches d.b.h. are seldom attacked.

Identification. – This is one of the few bark beetles that usually make very obvious pitch tubes on bark surface at site of attack (fig. 38). Pitch tubes are masses of red, amorphous resin mixed with bark and wood borings. Boring dust is evident in bark crevices and around base of infested trees.

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Figure 38 - Pitch tubes are usually evident at Mountain Pine Beetle attack sites.	Figure 39 - Mountain Pine Beetle gallery has a "crook" at the lower end.

Under bark, look for straight, vertical egg galleries with crook or "J" at start (fig. 39) which can extend upward 30 inches or more. Galleries are packed tightly with frass. Larvae (grubs) are present during fall and winter. Most pupate in late spring and adults emerge from the bark in midsummer to attack new trees. Mature adults are black and about three-sixteenths inch long. Infested trees fade within a year from yellow-green to red-brown, and can be heavily "woodpeckered."

Similar damages. – Boring dust is present with attacks by Ips spp. or other secondary bark beetles. Gallery pattern distinguishes mountain pine beetle.

Link to Images in Forestry Images

References.

Amman, G. D., M.D. McGregor, and R. E. Dolph, Jr. 1985. Mountain pine beetle. USDA For. Serv., For. Ins. & Dis. Leaflet 2,11 p., illus.

Anonymous. 1982. For. Insect & disease identification and management. USDA For. Serv., Northern Region; Idaho Dept. of Lands, Insect and Disease Control; Montana Dept. of State Lands, Division of Forestry. 192 p.

Furniss, R. L., and V. M. Carolin. 1977.  Western For. Insects. USDA Forest Serv., Misc. pub. 1339, 654 p., illus.

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