Why Is This Insect Such a Big Deal?

Mountain pine beetle is native to the Black Hills and has probably inhabited the Hills as long as there has been a pine forest. This insect goes through cycles where they become very abundant and then relatively rare. When the beetle population is very low only stressed or weakened trees, such as those struck by lightning, are colonized. However, about every ten years or so the beetle population increases and the beetles begin colonizing healthy as well as stressed trees. These outbreaks last for about five to 13 years after which the beetle population once again declines.

The first recorded outbreak in the Black Hills occurred in the late 1890s. An estimated 10 million trees were killed during this outbreak. Approximately five outbreaks have occurred since that time though none has reached the same magnitude. The outbreak in the early 1970s resulted in the loss of more than 440,000 trees. The last outbreak occurred from 1988 to 1992 and resulted in the death of approximately 50,000 trees. Beetle populations are increasing and are expected to continue to increase during the next five years.

Severe outbreaks can increase fire hazard as well as stream flow. The snags, however, are also beneficial as habitat for cavity-nesters.