The seemingly never-ending battle against bark beetles in the forests of Rocky Mountain National Park in Colorado will continue this spring and summer as crews spray an insecticide on stands of trees thought to be at risk from the beetles.

This year's mitigation work also calls for removing hazard trees, prescribed burns, utilizing an air curtain burner, and pheromone treatments, park officials say. The park’s priorities for mitigation of the effects of beetles are focused on removing hazard trees and hazard fuels related to the protection of life and property.

Starting in late April and ending by Memorial Day weekend, the park is planning to apply a Carbaryl based insecticide to up to 1,500 high-value trees to protect them from bark beetles. Insecticide will be applied from the ground and sprayed onto individual trees to repel beetle attacks.

Treatment will occur in the following developed areas of the park: Aspenglen Campground, Moraine Park Campground, Fire Management offices, Hollowell Park and Upper Beaver Meadows picnic areas, and housing areas including Kaley Cottages, Wild Basin Entrance and Deer Haven, Mill Creek Ranger Station, and Tuxedo Park.

Temporary closures to the public and employees will be in effect during spraying operations.

Last year, approximately 2,500 trees were treated and nearly all of these trees were effectively protected from bark beetle attacks, the Park Service said. Treatment sites have been reduced on the east side of the park because infestation rates decreased in forests adjacent to high value trees. The frequency of treatment has been reduced to biennial application.

The park is also treating up to 300 high value limber pine trees with Verbenone pheromone packets to minimize infestation by bark beetles. Limber pine trees in the park are currently at risk of mountain pine beetle infestation and infection from white pine blister rust, a lethal non-native invasive fungus. Research is being conducted to identify if any limber pine trees within the park are resistant to white pine blister rust.

Spruce and fir trees are currently at risk of beetle outbreaks in mixed conifer forest types. In 2015, the park began treating spruce trees at McGraw Ranch with pheromone packets to minimize infestation by spruce and fir beetles. In 2016, the park will continue treatment at McGraw Ranch and also apply pheromone packets to trees in the Endovalley picnic area.

Park staff will conduct hazard tree mitigation through tree removal throughout the year. Small scale, selective hazard tree removals will take place at: Bear Lake Trailhead, Beaver Meadows Visitor Center and housing areas, Endovalley picnic area, Bighorn Ranger Station, Aspenglen Campground, Hidden Valley picnic area, Sprague Lake picnic area, Moraine Park Campground, Moraine Park Stables, Tuxedo Park, Glacier Basin Campground, Lily Lake, Fern Lake Trailhead, and along road corridors including Highway 34, Highway 36, Bear Lake Road, and Old Fall River Road. Temporary access restrictions, such as 15-minute traffic delays, in immediate vicinity of tree cutting operations can be expected. More detailed information will be provided on upcoming tree removal projects along Trail Ridge Road on the west side of the park.