Pine bark beetles attack forests and stands of trees, which are stressed or appear to the beetles to be stressed. Mother Nature naturally thins our forest in many ways: wind, fire, flood, drought, insects (bark beetles) etc… In nature when trees begin to compete with each other for sunlight, water, and nutrients the trees become stressed and begin to die off. When the weak trees in a stand become stressed and begin to die, they emit an odor to which bark beetles key on and are attracted. Bark beetles flock to the unhealthy stand, and begin their relentless attack on the stressed and dying trees. Once the assault begins, many times healthy as well as unhealthy trees are attacked.
There are three types of pine bark beetles that attack live trees, Southern Pine Beetles (Dendroctonus frontalis), four species of Ips Beetles (Ips grandicollis, I. calligraphus, I. avulus, and I.pini ) and Black Turpentine Beetles (Dendroctonus terebrans).
Southern Pine Beetle (SPB) is the most destructive of the three types. There may be up to six generations of beetles per year. Adult SPB bore directly into the bark and mate. The females excavate the characteristic S-shaped egg galleries in the inner bark. Adults and larvae alike girdle trees quickly as they completely encircle the tree. The tree’s death is hastened by the introduction of blue-stain fungi which blocks the flow of nutrients and water to the crown of the tree. The pattern of movement is a key indicator when identifying this beetle, this movement across entire stands in short periods of time is what makes this beetle so devastating.
Ips Beetles are very similar in nature to Southern Pine Beetles. The adults and larvae completely girdle/encircle the inner bark of the trees, and with the aid of blue-stain fungi cut off the continued supply of nutrients and water, trees need for survival. Most of the time Ips beetles attack trees individually or in small groups, searching for weak trees throughout the stand. They move from one spot to another (this movement is an identifying characteristic pattern), but under favorable conditions can become epidemic and can devastate a stand.
Black Turpentine Beetles are the largest major bark beetle in our southern forests. These beetles create characteristically large pitch tubes which extend no higher than eight feet above the ground. There are usually only two full generations per year. This beetle does not introduce blue-stained fungi into the tree. The larvae feed in patches instead of completely girdling the inner bark of the tree, like Ips and Southern Pine Beetles. If the beetles are identified early, they can be treated with a chemical and in many cases the trees can be saved.
There is no way to prevent pine bark beetles from attacking our forests; however you can reduce the risk of attacks to stands of trees by ensuring they remain healthy. Good forest management, such as thinning at the proper times and densities, an effective prescribed burning program, fertilizing nutrient deficient stands, and removing or treating storm damaged trees promptly can keep your forest healthy and growing rapidly. If you suspect pine bark beetles in your stand, call your Southern Forestry Consultants, Inc. representative today and set up an inspection ASAP. Our foresters and biologists can help you identify and control these destructive insects.