The most damaging bark beetle species attacking Minnesota's pines are native beetles in the Ips genus. One common species is the pine engraver (Ips pini) and another the eastern fivespined ips (I. grandicollis). Red and jack pine are the most common hosts of Ips bark beetles, although white pine can also be infested, and in rare circumstances, weakened spruce and tamarack. There are several other non-Ips bark beetles that inhabit pines, but they are rarely problematic.
Ips bark beetles can quickly kill a few upper-canopy branches and eventually the entire tree. Needles on attacked branches fade from green to yellow-green to completely orange in a matter of weeks. The crowns of pines heavily attacked in late summer may not turn orange until late autumn or winter.
Fortunately, Ips bark beetles prefer to attack stressed pine trees or freshly-cut pine branches and trunks (called slash), so healthy trees are not usually harmed. Ips bark beetles cannot live in pines with loose bark or pines that have been dead for over a year.
It is not unusual to occasionally lose some pines in plantations from Ips bark beetles, so the loss of a few trees should not cause concern. Lightning strikes or thinning pines from late winter through summer without promptly removing slash can also promote Ips bark beetle attack of a few surrounding pines. In rarer circumstances, if an area with many pines is damaged by wind, fire, or extreme drought during the growing season, significant numbers of remaining healthy pines can be attacked and killed by Ips bark beetles. In recent years in Minnesota and Michigan, several prescribed fires in middle-aged red pine plantations promoted intense bark beetle outbreaks and serious losses within those plantations.
Location
Ips bark beetles are found throughout Minnesota.