Under normal conditions MPB populations remain small and only isolated, individual trees are affected. However, every 20-25 years MPB populations increase to epidemic levels and entire stands of trees can be killed.
Recent surveys have shown an increase in MPB populations along the Front Range and specifically in Jefferson County. We are seeing the beginnings of a new MPB epidemic. Jefferson County last experienced such an epidemic during the mid-1970's through the early 1980's. At that time, hundreds of thousands of ponderosa pine trees were killed and millions of dollars were spent on control measures. With MPB populations again on the upswing, measures should be taken to prevent widespread damage.
Most of the ponderosa pine trees currently infested with MPB are either infested with dwarf mistletoe or are under stress due to improper tree stand management. The most practical technique to protect your trees from MPB is to properly thin your trees. Closely spaced trees have to compete for water, sunlight, and nutrients, and are not healthy enough to resist insect attack. A healthy tree is able to produce enough sap to drown the invading pine beetle, "pitching it out".
Ways to help prevent MPB infestation