Gilpin County is experiencing a mountain pine beetle (MPB) epidemic. Pine beetles have changed the look of forests in the west and may well change our forests here in Gilpin County. Landowners can take steps to minimize the impact by understanding the MPB beetle life cycle and treatment options.

Beetle life cycle

The mountain pine beetle (Dendroctonus ponderosae) is a bark beetle native to western North America. The MPB usually takes one year to complete its life cycle, developing through four stages: egg, larva, pupa, and adult. Except for a few days during the summer when adults emerge and fly to new trees, all development takes place under the bark of infested trees. Female beetles lay tiny white eggs under the bark of pine trees in the late summer and early fall. The eggs hatch in 10-14 days and the larvae overwinter under the bark in breeding galleries. By July, most pupae have transformed into adult beetles that are black and 1/8- to 1/4-inch long.

Adults make tiny exit holes in the bark as they emerge from trees mid-July to mid-September. Within a few days of emergence, the beetles will enter new trees. There are usually enough insects in one tree to attack 2-10 additional trees. In Gilpin County, MPB attacks lodgepole, ponderosa, limber, and bristlecone pines. MPB carry the blue-stain fungi on their bodies and introduce them into the pine trees. The combination of the feeding beetles and spreading fungi kills the tree within a year of attack.

What forest owners can do

Although the MPB epidemic is too big to stop, you may be able to slow the spread by treating infected trees. Be proactive!

Now is the time to look for newly infested trees on your property. Look for reddish orange popcorn shaped pitch tubes on the tree trunk. Peel back an area of bark the size of a deck of cards just above the tubes. If you see live adult insects, eggs, or larvae in breeding galleries, the tree is still infected or “hot.” Infected trees can be treated to kill the beetles to reduce the spread of more beetles in the spring.

Treating infested trees

Infected trees will most likely die. If you want to kill the beetles inside the tree, here are the options which must be done before July 2023, when the beetles will emerge and fly to a new tree:

Chip the entire tree. Chipping kills the beetles.

Cut and haul the “hot“ tree to the Gilpin Slash Yard. Call ahead at 303-582-5004 to arrange drop-off. Be sure to tell them the tree is infected.

Peel the bark from the trunk with a chainsaw, draw knife, or Log Wizard. Removing the bark will kill the beetles. You can store peeled logs for future firewood.

Use green infested wood for firewood by July 2023. Cut and split wood, and allow it to dry out enough to burn before July. Mix green wood with dry wood in fireplace when burning. Be sure to use all the infested wood before July.

Solar treatment is an option, but is not often effective at our high elevation. Lay logs in a sunny, south-facing spot. Cover them with 6 mm clear plastic. Rotate the logs every few weeks. The treatment is meant to “cook” the beetles under the plastic. Often not enough heat is created at our high elevation.

Prevention

The MPB are native and play an important role in our forest ecosystem. Where there is lack of fire in overgrown forests, the beetles aid in natural forest thinning. There are two prevention options and neither is a silver bullet. It’s unrealistic to expect to prevent the beetles completely.

Verbenone, pheromone pouches, can be placed on trees throughout your property, to detract MPB. Effectiveness depends on tree species, beetle population levels, and many other environmental factors. Purchase verbenone pouches online from numerous retailers such as Forestry Distributing.

Spraying a high-value tree to prevent attack is effective, but not recommended on a large scale. The pesticide is nonselective and will kill other non-target species. Always use a licensed pesticide applicator and spray before MPB fly in July.

Learn More

CSU Extension is offering workshops (virtual and in-person options) about mountain pine beetle. Participants will learn about the beetle life cycle, how to identify beetle impacts on trees, control options to treat infested trees, preventative options, and what to expect for future impacts in Gilpin County and beyond. Presenting is Ben Pfohl, Colorado State Forest Service. Hosted by CSU Extension Gilpin County.

Jan 11, 2023 at 6:30 – 7:30 p.m. at Gilpin Library or Virtual In-person attendees: 15131 Highway 119, Black Hawk

Virtual attendees must register in advance- https://gilpin.extension. colostate.edu/classes/

Jan 13, 2023 at 4:30 - 5:30 p.m. at Gilpin Community Center (in-person only)

In-person only: 230 Norton Drive, Black Hawk

For questions on MPB, contact Jennifer Cook, Gilpin CSU Extension Director: 303-582-9106, Jennifer. cook@colostate.edu