Pine Beetle Facts

Bivoltine Cycles
We are currently seeing a bivoltine cycles, which means the beetles are able to complete two generations in a single year, whereas previously these insects would only complete one generation per calendar year. This phenomenon is linked to the warming climate. Warmer temperatures accelerate the development of the beetle hatches.

Pine Beetle Complex
In Colorado, we are currently seeing a pine beetle complex. There are two species, the mountain pine beetle and the roundhead pine beetle are both targeting pine trees.

Two-pronged Attack
Beetles kill trees in two ways. They damage vital inner bark that moves nutrients and water through the tree, by boring into the tree. Beetles also introduce blue stain fungus that clogs the vascular system of the tree.

Signs of a Beetle Infestation

• Popcorn-shaped masses of resin, called pitch tubes, on the trunk that may be brown, pink or white
• Boring dust in bark crevices and on the ground immediately adjacent to the
• tree’s base
• Woodpecker damage, where the birds have stripped portions of the bark in search of larvae, leaving accumulations of bark at the base of the tree
• Presence of live mountain pine beetles (eggs, larvae, pupae and/or adults)
• Exit holes on the bark’s surface where adult beetles have emerged
• Foliage turning yellowish to reddish throughout the entire tree crown, which usually occurs eight to 10 months after a successful attack
• Blue-gray appearance to the sapwood, that indicates the presence of blue stain fungi

Pine Beetle Lifecycle

LATE SUMMER
The beetles mate and form a vertical tunnel under the bark and produce about 75 eggs. This tunnel is called the egg gallery. The eggs will incubate for 10-14 days, with colder temps needing longer incubation periods.

WINTER
Larvae are able to survive the winter by metabolizing an alcohol called glycerol that acts as an antifreeze.

SPRING
As early as May, adults begin to emerge. These adult beetles are able to mate, and produce another generation of eggs in vulnerable trees.

SUMMER
A second generation of adults can begin in mid-August and continue through September.

Prevention & Management

There are several things you can do to protect your trees from pine beetles, prevention and early intervention is key to keeping your trees healthy. These options, when paired with proper plant health care and an Integrated Pest Management system are the best defense your trees have. A certified arborist can work wiht you to create a treatment plan that is best for your trees unique needs.

GOOD

Verbenone Packets

Verbenone packets are a pheremone that is attached to the trees externally. These packets signal to the beetles that there are already beetles in the tree. These can be effective but should be a part of a larger IPM program.

BETTER

Bole Applications

Bole applications of insecticide that is applied onto the exterior of the tree and can provide short-term protection. Trees will need this treatment annually, beneficial insects may be harmed as this treatment is non-selective.

BEST

Trunk Injection & Fungicide

Systemic trunk injection is an insecticide that is injected into the tree, and protects the tree for two years. When combined with a fungicide, this is the best treatment for your trees.