Although smaller than a grain of rice, the southern pine beetle is the greatest insect related risk timberland owners face. The reddish-brown or black insects bore through the bark of pine trees and create winding tunnels where they lay their eggs. Emerging larvae feed on the inner bark (the living portion of the tree trunk) until adulthood. They effectively girdle the tree as they build egg galleries and feed. The beetles also introduce wood-staining fungi into the trees, clogging the trees' water-conducting tissues, hastening their death and reducing the value of the wood. When adult beetles emerge from an infested tree they normally fly in the direction of the prevailing wind, since they are extremely poor flyers. This knowledge assists in planning salvage harvests.
Normally, southern pine beetles attack and kill stressed, injured or slow growing trees, such as mature pine stands. However, during years when populations reach epidemic proportions, even healthy trees can be attacked and overwhelmed. All timberland owners need to be able to recognize signs of pine beetle infestations, because it is critical to act quickly when these signs first become evident. It is the only way to prevent huge losses in mature pine stands.
How Can You Recognize Southern Pine Beetle Damage?
- Needles of infested pines turn yellow or straw-colored within two or three weeks of attack, before finally turning reddish-brown.
- Reddish-brown particles of boring dust may be seen in bark crevices and at the bases of dead or dying trees.
- Small light-yellow to reddish-brown pitch tubes, often resembling popcorn, may be seen on the bark in the middle and upper sections of the trees.
- Upon removal of a section of bark, winding S-shaped egg galleries may be seen. C-shaped larvae, pupae, and new adults may sometimes be seen within the bark itself.
Salvage removal or harvesting infested trees is the preferred direct control method since infested trees are removed and utilized, giving the landowner some financial return. Prompt treatment after spot detection will minimize additional timber loss from spot growth. When salvage of a spot is not feasible or must be delayed for long periods, active infestations should be treated by the cut-and-leave method.
The cut-and-leave method is an effective means of controlling small remote spots that cannot be salvaged. The method involves felling infested trees in a prescribed manner and leaving them in the forest. The treatment disrupts beetle spot growth and disperses the emerging adult beetles. Spots should be treated only if they contain freshly attacked trees. A buffer strip or "zone" of green, uninfested trees must be felled and left around each spot to assure that all newly attacked trees are included in the treatment.
It is extremely important that you get prompt professional advice, if you suspect that you have a Southern Pine Beetle problem. Because the needles will stay green for weeks following the attack of a tree, often the infestation has spread widely by the time a landowner notices the brown needles.
Give us a call if you feel you have a problem or if you would like a “Risk Assessment” for your pine stand.
Reprinted from “Forest Management News” Spring 2003, Volume 23 Number 1, published by Timber Marketing & Management of the Carolinas, Inc.