Southern Pine Beetles
The southern pine beetle is the most destructive insect pest in the southern United States.
This aggressive tree killer is a native insect that lives predominantly in the inner bark of pine trees. Trees attacked by the southern pine beetle often exhibit hundreds of resin masses or pitch tubes on the outer tree bark. Southern pine beetle feed on phloem tissue where they construct winding S-shaped or serpentine galleries. The galleries created by both the adult and their offspring can effectively girdle a tree, causing it’s death. Southern Pine Beetle also carry, and introduce into trees, blue-stain fungi. These fungi colonize xylem tissue and block water flow within the tree, also causing tree mortality. Consequently, once Southern Pine Beetle have successfully colonized a tree, the tree cannot survive, regardless of control measures.
The Southern Pine Beetle at times is an exception to the general rule that bark beetles are generally scavengers of dead or severely weakened trees. When population are high, Southern Pine Beetle will attack and kill trees that otherwise live for many additional years. Because the species can develop from egg to reproducing adult in as little as four weeks, there is relatively little time to keep them from colonizing new trees.
The best way to identify a species is to remove some bark and look at the size and shape of the beetles and their associated galleries. The Southern Pine Beetle is smaller with rounded back ends. It is about half the size of a grain of rice while the larger black turpentine beetle is twice as big. The three Ips beetles all have scooped-out rear ends with small spines around the margins. Southern Pine Beetles make winding intersecting egg galleries packed with boring dust. Black turpentine beetles tunnel horizontally. Ips beetles make clean galleries radiating out from a nuptial chamber made by the male when he attacked the tree.
Most infested pines are discovered when the needles throughout the crown change from normal dark green to a light green, yellow or red. On close examination of the trunk, there are holes about the size of pencil lead where the beetles have chewed through the bark. A resistant tree will flood the attack site with resin resulting in pop-corn like pitch tubes on the loblolly pines and brown runny streaks on slash and longleaf pines. A moisture-stressed tree may have no resin. Look closely for boring dust on bark ledges, leaves and spider webs around the base of the tree.
There are a number of ways to prevent beetles from developing in and dispersing from infested bark. Sometimes a cluster of infested trees can be cut down and sold to a wood producer where the bark is quickly removed and burned while the wood is processed for pulp or lumber. In urban situations, a homeowner must contact a tree service to cut a tree and kill the beetles. Pines should be felled and cut in short sections and an insecticide should be applied. Unfortunately, the best pesticide for control (Dursban and Lindane) are off the market and other insecticides that are labeled for bark beetles have not proven effective. Stumps of the trees can be infested or can be a source of a new infestation and should be removed as well.