GILPIN COUNTY, Colo. -- With warmer weather moving in, the U.S. Forest Service is trying to get a jump on pine beetles.

Crews started spraying pine trees in campgrounds this week to prevent infestations.

The pesticides are so expensive and the forest is so vast, they can’t possible spray all the trees. So, crews use red spray paint to mark the healthiest trees, and when those have been sprayed, they use blue dots to mark them as complete.

“It’s a mountain pine beetle epidemic,” said U.S. Forest Service biologist Maribeth Pecotte.

Clad in rubber suits and respirators, crews are trying to save the forest.

“We contract out with companies that come spray with the insecticide carbaryl. We start from the bottom up. Spray about 35 feet up and make sure we get full coverage all the way around the tree,” said forestry technician Colin Hutten.

“When the beetles infest the tree, the tree dies. And so whenever you have a lot of people in close proximity to dead trees there’s a risk of dead trees falling on people,” said Pecotte.

Temporary signs warn campers of the treatment in Gilpin County, while a permanent sign marks a spot for the campground host. And while they’re willing to host people here, the same is not true for beetles.

“We’re doing what we can, but we’re not going to get them all,” said Hutten.

And although some have called the attacks catastrophic, the forest service says it is simply Mother Nature taking its course.

“Absent the forest service to manage the forest, Mother Nature does it through bugs and fire.”

Many experts estimate 90 percent of the state’s lodgepole pines will be dead in five years.