• Spruce beetles are only ¼ inch long
• Spruce beetles infest Sitka, white and Lutz spruce (white/Sitka hybrid) most often, and attack black spruce only rarely
• Beetles live in the thin, phloem (growing) layer between the bark and the wood. Therefore the wood remains undamaged by the beetles and useable for construction for some time.
• One female beetle may lay from 10 to 150 eggs in "galleries" constructed beneath the bark in the phloem tissue.
• A large, downed spruce tree may contain more than 100 beetles per square foot of bark.
• Beetles emerge from infested tree and fly to new host trees from mid-May until mid-July (when temperatures are above 60° F).
• Spruce Beetles feed and breed on wind-thrown, fallen or injured trees wherever there are spruce forests. When conditions are right, beetle populations may outgrow the supply of down trees and move into nearby living trees, especially mature spruce stands
• In the current outbreak, spruce beetle activity in Alaska was mapped on over 1.3 million acres based on statewide aerial surveys in 1997. Cumulative beetle activity now totals over 3 million acres statewide since 1989 based on the annual aerial surveys.
• In the past 25 years beetle outbreaks have resulted in the loss of an estimated two billion board feet of timber in Alaska
• Since the mid 1970’s beetles have killed mature spruce trees on 1 million acres of the Kenai Peninsula – about 50 percent of the peninsula’s forested land.
• Human activities such as fire suppression and improper disposal of slash enhance conditions for beetle outbreaks; as do natural occurrences as blown down, fire scorched or flood damaged trees.
• Fast growing, healthy trees are more resistant to beetle attacks than slow growing unhealthy trees.
• Beetles can emerge from infested firewood and attack living trees.
• Beetles produce chemicals called pheromones to communicate with other beetles – for mating, to locate susceptible host trees and to repel other spruce beetles. Spruce trees also produce chemicals that affect beetle behavior. These chemicals show potential for modifying beetle behavior and reducing the severity, or even preventing, damaging infestations.
• Some EPA-approved insecticides have provided 100 percent protection from beetle attacks for at least two years, based on research results.

Spruce Bark Beetles in Firewood 
Spruce bark beetles attack and breed only in spruce. Birch, hemlock, aspen, cottonwood and other trees are not at risk. Spruce bark beetles spend most of their life in the phloem tissue between the bark and the wood of a host tree. Adult beetles emerge in the spring and bore through the bark of a new host tree. Female beetles excavate galleries in which to lay eggs. The newly hatched larvae create feeding tunnels at right angles to the larger egg galleries, where they complete their one or two year life cycle. 

If numerous beetles attack the tree, the resulting brood can girdle and kill the tree. Spruce beetle prefer to attack recently windthrown trees, but they also attack and kill standing trees that are weakened or diseased. Slow growing and less vigorous trees are also attacked when conditions favor beetle dispersal. 

Trees killed by spruce beetles are often used as firewood. During the first winter after infestation both larvae and adult beetles may be present under the bark. Adult beetles may also be under the bark around the base of the tree through the second winter, and may emerge the following spring. Two years after the attack, beetles have left the tree. A two-year life cycle is most common in Southcentral Alaska.

Adult beetles over-wintering under the bark of firewood emerge when warmer weather arrives and seek out new host material, often a valuable landscape tree near the woodpile. By examining spruce logs to be used for firewood, and following suggestions below, you may avoid spruce beetle infestations in your live standing trees. For more information about spruce bark beetles, contact the Alaska Cooperative Extension (786-6300), the USDA Forest Service (271-2575), or your local State Forestry office (269-8460).

Condition of spruce firewood & ways to reduce beetle populations:

Fresh log with green needles when cut; bark peels away from wood smoothly; wood not split.

• Store only enough firewood for a single winter’s use. 
• Split into stove-size pieces to dry out; stack loosely or separate to allow maximum air circulation. 
• Dry wood discourages new spruce beetle attacks. 
• De-bark log to eliminate potential beetle habitat.

• Store only enough firewood for a single winter’s use. 
• Split into stove-size pieces to dry out; stack loosely or separate to allow maximum air circulation. This will dry out the larvae and their food source. 
• De-bark log to eliminate larvae and habitat. 

• Split and use prior to next spring to kill adult beetles that will emerge at that time. 
• Fire-scorch the outer portion of the bark, killing beetles beneath, but keep the bulk of the wood intact (messy, but intact) for future use. 
• Consider preventive measures on surrounding live spruce trees. 
• See fact sheet "Spruce Bark Beetles; Control Options for the Home and Lot Owner".

• Spruce beetles will not attack well-seasoned wood and normally gone from trees that have been dead for more than three years ( though beetles and other insects may enter the wood). Old wood, free of spruce beetles, is not a potential spruce beetle infestation source.