What is the Southern Pine Beetle?

HOST: All Pines

IMPORTANCE: The southern pine beetle is considered the most destructive forest insect in the South. Weakening of the trees by flooding, windstorms, and especially drought commonly precedes these outbreaks. Trees of all sizes are attacked, but usually those larger than six inches are infested first. A few trees to several thousand will be killed in spots or patches.

DESCRIPTION OF THE INSECT: The brown to black beetle is about 1/8 inch long. Its hind end is rounded, in contrast to the scooped out posterior of Ips beetles. The larvae are white with a reddish-brown head and the pupae pure white. Fully grown larvae and pupae are approximately 1/8 inch in length. The eggs are white, and very visible to the eye.

SIGNS OF ATTACK: The first indication of attack is usually the yellowing or browning of the needles. Examination of the trunk of the tree will usually reveal white, yellow, or sometimes red-brown pitch tubes, about as large as a wad of gum. Under unusually dry weather conditions, pitch tubes may be very small or absent and only reddish-brown boring dust will be present. Examination of infested trees by removal of the bark will show a distinctive winding "S" shaped gallery pattern. This pattern is quite different from the "Y" or "H" shaped gallery pattern of Ips beetle and is a good identification characteristic if no adults are present. Active spots or patches of infestation are distinctive also in that the center trees have dark reddish-brown foliage gradually changing until those on the edge have light greenish or yellowish green foliage.

HABITS: The adult beetles are usually attracted to weakened trees. In epidemics, however, they attack trees that appear to be healthy and vigorous. Initial beetle attacks are in the mid-trunk area and then up and down the length of the tree. The adult beetles bore through the bark and then excavate long winding "S" shaped galleries. Eggs are laid in niches along these galleries. The larvae feed in the cambium area until they are grown and then excavate cells in which to pupate near the bark surface. After pupation the adult beetles chew through the bark and emerge. The complete life cycle of the attack, takes from 25 to 40 days to complete, depending on the temperature.

The Southern Pine Beetle situation is the best it has been in years. Statewide the number of infestations has decreased 59 infestations containing 2,690 active trees in February to 25 infestations containing 1,010 active trees. Most of these are in the Southwest Region (16 spots with 870 trees). The other Regions have NE- 9 spots with 140 trees, SE-0 spots, and NW 0 spots. There have been no epidemic counties in 2003. Last year at this time, Alabama had 1,012 spots containing 100,134 infested trees and 21 counties were epidemic. The cold wet winter and spring affected the SPB population and reduced the numbers drastically. If the weather continues wet this summer, the SPB situation will be within limits that can be handled. Normally the number of spots detected in the January/ February flight will increase by 10 fold in the summer months, but the numbers are decreasing. Landowners are being encouraged to control the 25 spots now and stop this infestation from reaching epidemic levels later this summer. The next SPB detection flight will be June / July. 
 

Southern Pine Beetle Control

Suppression is accomplished by an integrated approach in which three recommended techniques are involved. Emphasis is placed on control by timely removal and utilization of merchantable infested material. Unmerchantable material (small trees, infested bark, infested tops, etc.) should be either piled and burned or, as a last resort, chemically treated. Control efforts should be a year-round project; although, winter control is particularly important because brood densities tend to be higher and concentrated in a fewer number of trees. Research has indicated that control of one infested tree during the winter months may prevent 10 trees from becoming infested the following spring.

(1) Removal of Infested Trees by Salvage.

When infestations occur in trees of merchantable size and are readily accessible, infested trees should be removed. Because time is of the essence, logging of the infested material should begin IMMEDIATELY.

To minimize the possibility of spreading beetle infestations, prompt processing of infested material at nearby mills is recommended. Slabs and infested bark should be destroyed by chipping or burning. Encourage the infested logs to be used first. If the logs are going to lay on the log deck for several days, spray the logs.

Success in southern pine beetle salvage control hinges upon removing all pines with fresh attacks and those with developing beetle broods. The best insurance is to cut a buffer strip of uninfested green pines around the active head of a spreading spot. This tactic interrupts the beetles' attractant source and stops their advance. The buffer strip also provides a margin of error, just in case infested pines were initially overlooked.

WIDTH OF STRIP - The easiest rule is to make the width the same as the height of the infested trees. Example: The infested trees are 65-feet tall; cut the buffer to a width of 65-feet.

WHERE TO START MARKING THE BUFFER - Start from the freshly attacked green pines and make the buffer from there into the green, healthy pines.

WHERE TO START CUTTING - Start with the outermost green pines and cut back towards the old, "dead," vacant pines (those are the ones with very loose bark which can be removed easily). There is no need to cut these "dead" trees. For effective control, cut only the green, freshly attacked pines and pines with developing broods. In the summer, these generally are the green, fading, and some of the red-topped trees.

(2) Piling and Burning.

Cutting infested trees, piling the stems and thoroughly burning the bark surface may be used to suppress unmerchantable or inaccessible southern pine beetle infestations. The entire bark surface of infested trees must be thoroughly burned to insure effective control.

(3) Chemical Control - Use Only as a Last Resort.

For chemical to use contact a forester who is a Certified Pesticide Applicator.

Spray only spots that are inaccessible to salvage. Cut and buck all infested trees into workable lengths. Wet entire bark surface thoroughly (to the point of runoff) with a coarse spray from a low-pressure sprayer. Turn logs two or three times to insure all surface is wet.

Spray infested stumps or trees damaged by salvage crew. Cut and spray unmerchantable infested trees. Fell infested trees toward the center of the spot. Spray tops only if they are infested. Never spray trees from which beetle has emerged. This allows natural enemies to complete their development.

HABITS: The adult beetles are usually attracted to weakened trees. In epidemics, however, they attack trees that appear to be healthy and vigorous. Initial beetle attacks are in the mid-trunk area and then up and down the length of the tree. The adult beetles bore through the bark and then excavate long winding "S" shaped galleries. Eggs are laid in niches along these galleries. The larvae feed in the cambium area until they are grown and then excavate cells in which to pupate near the bark surface. After pupation the adult beetles chew through the bark and emerge. The complete life cycle of the attack, takes from 25 to 40 days to complete, depending on the temperature.