Mountain Pine Beetle Spraying FAQs

Frequently asked questions about the mountain pine beetle.

When does the mountain pine attack trees in Colorado?

Typically the mountain pine beetle is in flight during the months of June and early July. Before that it is developing under the bark in its larval stage.

There are mountain pine beetles on my tree. Can you stop it?

The short answer is no. Preventive tree spraying is the best way to prevent beetles from infecting a tree. Other tactics such as pheromones which attract and trap beetles and tree health care such as fertilization and watering are less effective.

When should you spray for mountain pine beetle?

The only time to effectively spray to prevent beetle infestation is between April and June. If the application is done in early spring, there must be some sort of sticking agent in the mix so that the active chemical stays on the bark through June and early July. After mid-July the beetles go away making any spraying ineffective.

Are the insecticides dangerous?

We primarily use permethrin based products that are only available to commercial grade applicators. We take great care especially with fish and cats, which can be poisoned. The pesticides are toxic when wet so we always advise people to stay out of the way for about 40 minutes, more than enough time to dry in the Colorado climate.  Also, following the label directions for personal protective equipment is required by law.

Some applications that contain carbaryl are available to the general public (and unlicensed tree sprayers). This is nasty stuff (that’s an arborist term) and we reiterate to follow label directions closely.

I thought mountain pine beetles weren’t in the Highlands Ranch area?

We have seen mountain pine beetle infestations from Highlands Ranch to Castle Rock. USDA scientists have projected that by 2012, any community on the Front Range with pine trees will be effected. That is why we are doing preventive spraying now. Currently, areas such as Castle Pines, Pinery,  Parker,  Highlands Ranch and parts of  Highlands Ranch are the most vulnerable but short of a chemical cure that kills off infestations, mountain pine beetle is a part of the Front Range arboriculture.