Coniferous trees like pines and spruces are popular among Colorado homeowners because they retain their green color all year round and can often handle harsher conditions than other trees. However, plenty of pests target these trees, and some beetles target only a single type of tree rather than an entire family. For example, the spruce beetle primarily attacks spruces.
Unfortunately, the spruce beetle has also experienced numerous booms in population lately in Colorado. Find out where the pest comes from, why it’s not always a problem, and what to do if you suspect your spruces are being damaged by this beetle.
1. Native Pest
Unlike many other diseases and insects damaging trees across Colorado, the spruce beetle is actually a native resident and a natural part of the ecosystem. Yet it is also a species that has the potential to seriously damage entire populations of spruces when the conditions are right.
During most years, adult beetles only reproduce in trees that have fallen due to damage or other diseases. If enough trees fall all at once, such as due to a high wind storm or a mudslide, the resulting increase in population can force those new generations to bore holes in living trees instead. Infestation weakens and eventually kills spruces, especially in epidemic conditions.
2. Current Epidemic
Certain parts of Colorado have been experiencing an epidemic of spruce beetles since the early 2000s. While the sheer number of affected acres is slowly starting to drop, the Forest Service still considered the state under epidemic conditions as of 2017. This means that the beetles can spread far from the most heavily infested acres to damage the trees of millions of homeowners throughout the state.
Unlike many other pests, the spruce beetle takes between one and three years to complete a life cycle. Trees often don’t show serious symptoms of infection for a few years after the beetles move, leaving homeowners unaware until trees turn red and die back completely. Paying close attention to holes in the bark or resin deposits can help you spot beetle infestations before it’s too late to treat.
3. Tree Size
Spruce beetles in particular prefer mature trees when making the move from downed trees to living ones. Beetles are particularly drawn to trunks that are eight inches in diameter or greater, but they have been found to infest trees just four to six inches wide when necessary. Treating and inspecting your largest spruces first will help you detect the earliest warning signs that spruce beetles are moving in.
4. Serious Effects
During normal years of development, the spruce beetle will stay limited to dead wood and a few aging or already dying older trees. When the beetles move into younger and otherwise healthy trees, they cause the trees to dry rapidly as they interrupt the flow of sap to the top of the tree. Spruces often die from the top down, changing color and drying out dramatically in a matter of months.
5. Treatment Options
If you manage to spot the holes made by spruce beetles before the tree shows significant signs of damage, you can definitely treat the tree to kill the beetles. The Forest Service recommends numerous pesticides for use on infected spruces, but you’ll need professional help since most sources recommend spraying 25 vertical feet or more of the trunk.
Need help taking care of your Colorado spruce trees? Contact our team here at Ross Tree Company. We can help you maintain the trees you already have, remove any damaged or dying trees, and give you advice on avoiding diseases and pests in the future.