Link Link Link

common name: black turpentine beetle
scientific name: Dendroctonus terebrans (Olivier) (Insecta: Coleoptera: Curculionidae: Scolytinae)

Introduction - Distribution - Description - Biology - Hosts - Detection - Prevention and Management - Selected References

Introduction (Back to Top)

The black turpentine beetle, Dendroctonus terebrans (Olivier), or BTB, is one of five common species of pine bark beetles in the southeastern United States. Black turpentine beetles bore into the inner bark of stressed or injured pines (Pinus spp.), where they breed and feed on phloem tissue. Adults are strongly attracted to volatile pine odors and readily breed in fresh stumps. Attacks on standing trees usually occur on the lower 1 to 2 m of the trunk or on large roots. Light attacks may kill only localized sections of phloem tissue, but numerous attacks per stem result in tree mortality. Infestations commonly occur in pine stands affected by recent logging activity (e.g., thinning), fire, mechanical injury, storm damage, climatic stress, or competition (USDA Forest Service 1985, Dixon 1986).

Historically, BTB has been a major pest of pines wounded or treated with herbicides in naval stores production (Smith and Lee 1972, Goldman et al. 1979). When local populations are sufficiently high, apparently healthy trees can be killed (Smith and Lee 1972). However, BTB infestations do not exhibit the rapid and devastating expansion characteristic of the closely related southern pine beetle, D. frontalis, and typically result in scattered, patchy and limited pine mortality.

Distribution (Back to Top)

The BTB is found throughout the eastern United States from coastal New Hampshire south through Florida and west to Texas and Missouri. The northern range of BTB overlaps that of the red turpentine beetle (D. valens LeConte) which is similar in appearance and behavior.

Description (Back to Top)

Adults are cylindrical, dark reddish-brown to black, and 5 to 8 mm in length (notably larger than the southern pine beetle, D. frontalis, which is 2 to 3 mm long). The head is convex in front and has clubbed antennae. The pronotum, the hard cover on top of the insect's midsection, widens posteriorly and does not conceal the head when viewed from above. The rear end of the wing covers is rounded (convex), which helps to distinguish Dendroctonus from the Ips engraver beetles.

Dorsal view of an adult black turpentine beetle, Dendroctonus terebrans (Olivier). Its large size, trapezoidal pronotum, and rounded declivity distinguish it from all other bark beetles infesting pines in the South.

Figure 1. Dorsal view of an adult black turpentine beetle, Dendroctonus terebrans (Olivier). Its large size, trapezoidal pronotum, and rounded declivity distinguish it from all other bark beetles infesting pines in the South. Photograph by David Almquist, University of Florida.

Lateral view of an adult black turpentine beetle, Dendroctonus terebrans (Olivier). Some adults have the red-brown coloration shown here although the majority of adults are black.

Figure 2. Lateral view of an adult black turpentine beetle, Dendroctonus terebrans (Olivier). Some adults have the red-brown coloration shown here although the majority of adults are black. Photograph by David Almquist, University of Florida.

The adult black turpentine beetle , Dendroctonus terebrans (Olivier), (right) is 5 to 8 mm in length, much larger than the southern pine beetle, Dendroctonus frontalis Zimmermann, (left). A grain of rice (middle) is inserted for size comparison.

Figure 3. The adult black turpentine beetle , Dendroctonus terebrans (Olivier), (right) is 5 to 8 mm in length, much larger than the southern pine beetle, Dendroctonus frontalis Zimmermann, (left). A grain of rice (middle) is inserted for size comparison. Photograph by Southern Forest Insect Work Conference Archives, www.forestryimages.org.

Mature larvae are about 12 mm long, creamy white, legless, and have reddish-brown heads. Pupae are waxy-white and of size similar to adults (Goyer et al. 1980, USDA Forest Service 1985) .

The pupa (top) and larva of the black turpentine beetle, Dendroctonus terebrans (Olivier).

Figure 4. The pupa (top) and larva of the black turpentine beetle, Dendroctonus terebrans (Olivier). Photograph by Gerald J. Lenhard, www.forestryimages.org.

Biology (Back to Top)

Adult females initiate attack on the lower tree bole or root collar by boring a hole through the outer bark. Trees with sufficient resin pressure typically produce a large mass of resin and reddish boring dust called a "pitch tube" at the site of attack. A female beetle that successfully overcomes this resinous host defense mechanism initiates gallery construction in the phloem and is then joined by a male. Tree colonization is mediated through beetle pheromones and volatile host attractants (Smith et al. 1993).

Pitch tubes of the black turpentine beetle, Dendroctonus terebrans (Olivier), occur on the lower trunk and may be as large as a half dollar.

Figure 5. Pitch tubes of the black turpentine beetle, Dendroctonus terebrans (Olivier), occur on the lower trunk and may be as large as a half dollar. Photograph by Wayne Dixon, FDACS-DPI, www.forestryimages.org.

Close up of a pitch tube on slash pine caused by the black turpentine beetle, Dendroctonus terebrans (Olivier).

Figure 6. Close up of a pitch tube on slash pine caused by the black turpentine beetle, Dendroctonus terebrans (Olivier). Photograph by Albert E. Mayfield III, FDACS.

Adults spend about two weeks constructing galleries about 1 cm wide and 20 to 30 cm long on the face of the sapwood, typically in a downward direction from the entrance hole. The female then lays about 100 eggs in an elongate batch along one side of the gallery. Egg hatch occurs 10 to 14 days later.

The egg gallery produced by adult black turpentine beetles, Dendroctonus terebrans (Olivier), starts with a short horizontal segment, then extends downward as the female produces eggs.

Figure 7. The egg gallery produced by adult black turpentine beetles, Dendroctonus terebrans (Olivier), starts with a short horizontal segment, then extends downward as the female produces eggs. Photograph by Ronald F. Billings, Texas Forest Service; www.forestryimages.org.

Larvae feed side by side, creating a large, fan-shaped gallery or cavity that may fill with resin and frass. Mature larvae eventually tunnel off of the expanded cavity and create pupation cells.

Feeding larvae of the black turpentine beetle, Dendroctonus terebrans (Olivier), and fan- or D-shaped larval gallery.

Figure 8. Feeding larvae of the black turpentine beetle, Dendroctonus terebrans (Olivier), and fan- or D-shaped larval gallery. Photograph by James R. Meeker, FDACS; www.forestryimages.org.

Young adults chew holes in the bark, exit their brood tree and disperse to colonize suitable host material. There are up to three overlapping generations per year in Florida and all life stages can be found year round (Smith and Lee 1972, Godbee and Franklin 1976, USDA Forest Service 1985). Fatzinger (1985) found peak trap captures in North Florida to occur in March, July and October.

The BTB is capable of vectoring blue stain fungi into the sapwood of its hosts (Barras and Perry 1971, Rane and Tattar 1987). Because BTB-attacked trees often survive, however, fungal colonization of the xylem may be less frequent, less pathogenic, or less extensive than blue stain introductions made by Dendroctonus frontalis and Ips engravers that result in rapid plugging of the xylem and hastened tree mortality. Tree mortality from BTB is, therefore, often a result of accumulated attacks over multiple generations or years.

Hosts (Back to Top)

All species of southern pines (Pinus spp.) and red spruce (Picea rubens Sarg.) are suitable hosts. Slash (Pinus elliottii Engelm.) and loblolly (P. taeda L.) pines are common hosts in the southeastern U.S. (USDA Forest Service 1985). In other locations, native and non-native hosts include pitch pine (P. rigida Mill.), eastern white pine (P. strobus L.), black pine (P. thunbergiana Franco) and Scots pine (P. sylvestris L.) (Wood 1982, Rane and Tattar 1987).

Detection (Back to Top)

Signs and symptoms of BTB attack include:

Prevention and Management (Back to Top)

Promoting and maintaining the health of pine trees and stands is the best way to prevent BTB attacks.

Preventative strategies in forest stands include:

Thinning should be conducted before trees begin declining in growth due to root and crown competition. Avoid thinning when active bark beetle infestations are present within or adjacent to the stand. In areas where annosum root disease, caused by the fungus Heterobasidion annosum (Fr.:Fr.) Bref., has been or could be a problem, consider treating fresh-cut stump surfaces with borax following cool-season thinnings to help prevent root disease development in residual pines (Barnard 1999).

As for control, when BTB infestations are small and/or sparsely scattered throughout a stand, the best course of action is usually to let them die out on their own. Cutting and removing isolated infested trees or small "spot" infestations, as is done to control southern pine beetle infestations, is not recommended. In some cases such selective removals may exacerbate BTB problems by producing fresh host odors, fresh breeding material, and additional stress or injury to the residual stand. If tree mortality is progressing to unacceptable levels, a stand-level clearcut or a block removal of a generally infested area is preferable to selection harvests. Use of traps to control infestations and prevent attacks has not been successful (Fatzinger 1985).

For urban and residential landscape pines, preventative strategies include:

In some cases, the application of an approved insecticide to the lower 2 to 3 m of trunk may be warranted to protect high-value landscape trees from infestation. As a rule of thumb, trees on which the number of BTB pitch tubes is less than the diameter of the tree in inches are more likely to survive than those with greater attack densities; such trees may be good candidates for insecticidal treatment to prevent additional attacks.

Contact your local county Cooperative Extension Service office for current insecticide recommendations. Infested trees should be removed carefully to avoid injury to surrounding pines.

Selected References (Back to Top)