Mountain Pine Beetle Spraying FAQ
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 from mid – July through August. However, startling new data suggests their season is rapidly expanding according to ecologists at CU- Boulder. Beetles were caught as early as May 22nd and as late as September 20th.
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 prevent beetle infestation is to spray before they attack the pine tree. There are no remedial treatments once the pine beetle has colonized the tree. We time our pine beetle spray between April and June before the adult beetles emerge.
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 the summer.
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 Denver area?
We have seen mountain pine beetle infestations from Boulder 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, Boulder and parts of Denver 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.