(NOTE! Chemical Sprayingis Prohibited at Beaver Lakes)
A Native Species that Presents Us a Challenge
The Mountain Pine Beetle (MPB) lives in the bark of pine trees. They are native to Colorado. They prefer the larger, older trees (6″ diameter and larger). Their yearly life cycle kills pine trees. When they are few, they help by remvoing older, weaker trees. When conditions let them reach epidemic levels, they can overcome the defenses of healthy trees. Drought and the lack of sustained cold weather in Colorado has favored them; the beetles are killing many more trees. The one other factor that has led to this mass-killing of lodgepole pine is that the majority of our lodgepole pine forests in Colorado are at maturity, therefore they are both attractive to the beetles and at a weaker state than they would be if they were younger trees.
Diagnosis, Treatment, Replacement
The key to lowering the impact of the Mountain Pine Beetleon Beaver lies in understanding the insect. Diagnosis of your trees is the first step. The second step is control of your infected trees, in order to reduce the transmission of new infection, and to give the younger and healthier trees a better chance.
In the long run we can prepare for a healthier forest growth by encouraging a greater diversity of trees, which reduces the impact of the Mountain Pine Beetle as well as its cousin the Ips Beetle (the Ips beetle flies earlier than the MPB; the attached documents will show you the difference). Since treatment consists mostly of removing trees, we can take advantage of this opportunity to increase species diversity, planting limber pine and bristlecone pine, which do well at our elevation. Other pines such as Engleman spruce, blue spruce and subalpine fir may work as well.
Diagnosis: Pitch Tubes, Bark Study
A beetle chews into the bark of larger, older Lodgepole or Ponderosa pines, their favored environment. The tree defends by emitting resin, which can overcome the beetle. When the coordinated assault of many beetles is too great, the beetles enter the bark, leaving reddish and yellow pitch tubes of resin on the outside of the tree. This happens in the late summer and fall. You can also see saw dust on the ground and in parts of the bark, resulting from the beetles’ boring of entry holes.
Inside, the beetles mate and leave eggs along vertical grooves chewed into the bark/wood interface. The eggs hatch and become larvae, which carve their own curving channels left and right of the vertical “nuptial chamber.” The mating pair dies, leaving their offspring to winter and to start the process all over again next summer.
The Hatchet Job
In the fall you can use a hatchet to remove a small section of bark from a newly pitch-tube-covered tree and find the chambers and the larvae. An infected tree with live larvae, though still green, will inevitably die. It should be removed, but you must take action to prevent those larvae from successfully wintering and then flying to infect new trees.
Treatment: Infected Trees
An infected and still-green tree poses a threat to other uninfected trees. If you cut that tree down you can use one five techniques to remove the danger of beetle survival and flight.
1) Bury the wood underground.
2) Use a wood chipper to reduce the entire tree to chips.
3) Strip all the bark from the tree, cut the remaining wood into logs and split those logs. Foresters prefer this method. Attachments to chain-saws are available to facilitate bark removal.
4) Use solar exposure to kill the beetles. This is the plastic-wrap technique. Cut the trees up. Cover them with plastic with 6mil outdoor-rated clear plastic for a period of one year to kill the beetles. The wood must be completely wrapped and closed. The wood should be placed for maximum exposure to the sun. The wood should not not be more than two layers. The should be rotated 1/3 every 4 four months. Plastic is difficult to work with and not very efficient when covering many logs.
5) Burn all the wood immediately.
When is a Downed Tree Not a Threat?
When the beetles leave the tree they bore holes out through the bark. These holes are numerous, round, and completely clean (no resin). The tree’s needles will become pale. These trees may be cut and used for firewood with no precautions. Red trees are long past being a threat.
No Greenwood Cutting
The cutting of live trees is not recommended during the period of June through September. Cutting during this time may attract beetles to the area, especially if the slash and/or wood are to remain on site.
Removal to a Safe Site
If solar treatment has not begun by April 1st, sufficient time is not available to kill off the beetles in the wood before the flight begins unless the wood is covered with 6 mil clear plastic. In this instance, wood cut on or after April 1st must be hauled to a safe site. Safe sites are at least 1 mile in all directions from any MPB susceptible host tree, i.e. ponderosa, lodgepole, pinon, or limber pines.
Treatment: Uninfected Trees
Spraying is Prohibited at Beaver Lakes
Carbaryl is only preventive; it must be applied to healthy trees between May 1st and July 10th. It represents some danger to animals, and is lethal to to many non-target insects, particularly honeybees. It must be applied carefully and to very exacting standards. A spraying lasts for one year. Because of the danger to living things and water quality, the Board has chosen to prohibit chemical spraying at Beaver Lakes.
Pheromones
Verbenone has showed some effectiveness at minimizing some of the impact in low populations of Mountain Pine Beetle. The patches are placed on the trees. The pheromone tells the invading beetles that there is “no vancacy” in these trees.
Reducing the Risk for Your Uninfected Trees
— Minimize soil disturbance.
— Do not cut any trees during flight season (late June to September.)
— Promote your young healthy Lodgepoles by cutting large trees.
— Add new, non-susceptible trees. Make room for Aspens to expand.
Keep Your Wood Piles Away from Pine Trees