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Five major species of pine bark beetles are found in South Carolina. They are the Small Southern Pine Engraver (Ips avulsus), the Southern Pine Engraver (Ips grandicollis), the Coarse Writing Engraver (Ips calligraphus), the Southern Pine Beetle (Dendroctonus frontalis) and the Black Turpentine Beetle (Dendroctonus terebrans). The three Ips beetles are very similar in appearance except for size and the number of spines on the posterior margin of the elytra (wing cover). All are reddish-brown to black and range in size from 1/8 to ¼ inch in length. When viewed from above, the head is not visible. The posterior region of the wing covers and abdomen have a "scooped out" depression that is characteristic of the Ips beetles.
Southern Pine Beetles are brown to black and about 3/16 inches in length. The head is visible from above and has a median groove that gives the appearance of two "horns" projecting from the head.
The Black Turpentine Beetle is the largest of the major pine bark beetles, about ¼ inch long. It is reddish-brown to black. The head is visible when viewed from above.
Most species of pines found in South Carolina are subject to attack by the pine bark beetles. Trees under stress are much more susceptible. Some preference is shown for loblolly, shortleaf and Virginia pines.
The most severe and ultimately fatal injury is caused by larval (immature forms) feeding on the cambium layer (the layer of cells that produces the water-and food-carrying tissues of the tree) under the bark. Ultimately, the tree is girdled and the flow of nutrients and moisture is cut off. The adults bore into the bark and cut egg galleries, but in itself this injury is secondary. Activity by adults can introduce fungal diseases, also.
The primary symptoms include pitch-tubes, popcorn- or larger-sized balls of resin on the outer surface of the bark, reddish sawdust-like material on the bark, and a general decline of the tree. Decline is indicated by fading of the needle color from a rich green to yellow, red and brown.
All of the bark beetles have similar life histories. The adult beetles usually are attracted to trees under stress. Infested trees, in particular, are attractive to adult beetles. They bore into the bark and hollow out galleries. The females lay eggs in niches along the galleries. After about a week, the larvae hatch and start feeding on the cambium layer. When mature, they pupate (transform into a nonfeeding stage where the larvae change to adults) in cells constructed in the bark. When the adults emerge, a small exit hole is cut in the bark and the beetles fly to another tree. Several generations are produced each year.
The best control is to keep trees in vigorous, healthy condition. This will usually prevent the initial attack by adult beetles. Healthy trees have a heavy flow of pitch and can "drown" the beetles as they bore through the bark. It is not possible to prevent natural weakening factors such as old age, prolonged floods, fire, drought and lightning strikes from occurring. However, in the homeowner’s situation, water and fertilization go a long way toward keeping the tree healthy. Avoid injuring trees with riding lawnmowers.
If a tree is severely injured or struck by lightning, prompt removal of the tree will prevent beetle infestations. Avoid soil compaction and injury to trees during house construction. Also, do not leave only large, mature pines on the lot. These tend to be very slow growing and are much more susceptible to pine beetle attack.
During hot, dry weather, inspect the trees for the initial signs of attack. Prompt chemical treatment may save the tree. If a tree is beginning to show color changes in the needles, remove it as soon as possible. One infested tree can be the source of thousands of adult beetles that will spread to other pines in the yard and neighborhood. Spraying adjacent pines may reduce the possibility of infestation.
The key factors to remember for control of pine bark beetles are:
- Avoid damage to pines during yard work or construction;
- Keep pines healthy by watering and fertilizing them;
- Watch for pitch tubes and boring dust;
- Remove or spray infested trees immediately. In most cases, spraying a tree 40 to 60 feet tall is not an option for the homeowner. Consult a qualified tree care expert.
Consult your local county Extension agent for current insecticide recommendations and assistance in beetle identifications and control.
Prepared by Clyde S. Gorsuch, Extension Entomologist, Clemson University.
This information is supplied with the understanding that no discrimination is intended and no endorsement by the Clemson University Cooperative Extension Service is implied. Common and brand names of pesticides are given as a convenience and are neither an endorsement nor guarantee of the product nor a suggestion that similar products are not effective. All recommendations for pesticide use are for South Carolina only and were legal at the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies. Follow all directions, precautions and restrictions that are listed. (New 5/99).
The Clemson University Cooperative Extension Service