Preventative Spraying For Bark Boring Beetles | Blog | Front Range Arborists

Preventative Spraying for Bark Boring Beetles

Bark beetles are insects that attack many types of trees along the front range.

In the early spring, the borers that attack evergreen trees are the biggest issue. Ips beetle, Turpentine beetle, and Mountain Pine beetle all attack evergreen trees in Colorado. All of these beetles can be well controlled with preventative spraying before they emerge from their overwintering habitats.

Ips Beetle

These beetles will come out early, usually late March / early April. These beetles will attack a wide range of trees, including Spruce, Ponderosa Pine, Austrian Pine, Lodgepole Pine, etc.  These candidate trees should be sprayed from the top to the bottom of the tree, as most Ips beetles have a “top-down” killing effect on trees.

Turpentine Beetle

These beetles tend to attack Austrian pine and Scotch pine. They will attack the lower 6-10 feet of the tree and the root flare as well. These should be sprayed at the same time as Ips beetle for best control.

Mountain Pine Beetle

These beetles have been on the decline along the front range for the last few years, but still, show up in pockets around town. They attack Ponderosa, Lodgepole, and Austrian pine primarily. Sprays should be front he base of the tree up to around 30 ft., or when the trunk tapers to around 6 inches, whichever comes first. These beetles rarely attack trees less than 6 inches in diameter. Spraying for these candidate trees should be done in the May/June time frame.


Other Beetles To Be Aware Of

While the big three listed above are the most common, other bark beetles are around the front range.

Pitch Mass Borer attacks Pinion pine trees. Their attacks are quite noticeable because of the large pockets of sap (pitch) at the site of the attack.

Fir Engraver Beetle

These attack Douglas Fir trees, but have rarely been known to attack surrounding trees that aren’t of the same species when nothing else is available.

Lilac Ash Borer

Not to be confused with Emerald Ash Borer, which is still quarantined in the Boulder County area. These borers attack all Ash species we have along the front range. Look for small, round holes in the trunk, and larger branches. Should be sprayed in early to mid-April.


While this is not a comprehensive list of bark beetles that are in the front range or a full list of trees beetles will hit, these are the primary trees we see affected, and the primary beetles doing damage in the spring. If you have any questions about bark beetles or any issues with your trees, please call our office at (719) 635-7459 and we will be happy to assist you. And don’t forget, the best prevention for insects and disease is a healthy tree. Please make sure your trees are well watered, especially in the winter!


Find out more about how Front Range Arborists can help provide services to residential, commercial, and municipal institutions with all of our Tree Services: