Southern pine beetle |
|
The southern pine beetle is the most destructive forest insect in the southern United States. Because populations build rapidly to outbreak proportions and large numbers of trees are killed, this insect generates considerable concern among managers of southern pine forests. These tiny cylindrical beetles, averaging 2 to 4 mm in length or roughly the size of a grain of rice, are brownish to black with a broad head and a well-developed mouth for voracious chewing. |
|
The beetle begins life as an egg deposited in a winding “S”-shaped gallery in the cambium layer, between the bark and the wood of the pine tree. In this gallery they mature into adults. One life cycle or generation of beetles from egg to adult may take anywhere from 26 to 54 days, depending upon the season. While development of the beetle takes place throughout the year, it slows considerably in the winter and increases in the spring and summer as temperatures warm. Several generations of southern pine beetle occur annually. |
|
Crown discoloration is just one sign of beetle intrusion. As the beetles enter the trunk of the tree, small light yellow to white pitch tubes usually form. These masses of pitch are about the shape and color of popcorn and similar in size. In areas where the trees are especially weak, pitch tubes may not be formed. Instead, a collection of reddish boring dust can be found in the bark crevices or along the base of a tree. Other traces of evidence that the southern pine beetle leaves behind are the winding, “S”-shaped egg galleries in the cambium, as well a blue-stain fungus that the adult beetles introduce. Along with the girdling effect of gallery excavation, the fungus contributes to the death of the tree by eventually plugging the water-conducting tissues. |
|
|
|
| << previous | Pages 1 of 7 |
