|
| You are here:
Main >
Pine Beetle |
|
 Pine Beetle
Backgrounder:
Having spread to about 13.5 million hectares of British Columbia, including the Regional District of Okanagan, the bark beetle epidemic is the largest insect epidemic in the province’s history. Pine trees everywhere, including back yards and parks in urban, rural as well as wilderness areas are at risk of beetle attack.
 Infested and dying trees pose a risk to people, the environment and the economy. Dying trees, with their yellowed and red leaves reduce the aesthetic values of forest views. Private property owners experience loss when their once-beautiful, treed properties are reduced to open brush fields. Dead trees are a fire hazard and become dangerous when limbs and trunks begin falling. Healthy, live trees are important factors in water quality as well in erosion control. Infested trees cause new beetle populations to expand exponentially. In fact, each beetle infested tree contains enough beetle brood to infest between three and eight healthy trees in up to 20 generations per year. There are also major economic losses when forests lose timber volume and high-value mature trees. Blue staining, also caused by pine beetles, lowers wood’s commercial value.
Pine Beetle Biology
Though there are many bark beetle species native to British Columbia’s forests, only a few pose a significant risk to trees. Historically in the Okanagan, western pine beetle (Dendroctonus brevicomis) has been the most common pest of ponderosa pine trees with occasional outbreaks of mountain pine beetle (D. ponderosa). Western pine beetle only attacks ponderosa pines, while mountain pine beetle affects most pine species, including ponderosa, lodgepole, western white, whitebark and occasionally Scotch pines. Mountain pine beetle population have increased dramatically in higher elevation lodgepole pine stands and are now invading ponderosa pine trees in the Okanagan Valley.
Western Pine Beetle
Up to two generations of western pine beetle (WPB) are produced each year. Adults are dark brown to black and about 3 - 5 mm long, with stout bodies and hard shells. They begin emerging from the outer bark of infested trees in May and June, and sometimes as early as April. Adult WPB are good flyers, traveling long distances to find new pine stands. They bore into the bark of new trees, eating the tissues (cambium layer) that transport water and nutrients up and down the tree, causing the tree’s death. As the WPB feed and lay eggs, they make long, meandering tunnels or ‘galleries’. The galleries will cross and re-cross, creating complex networks.
 Adult western pine beetles carry a blue-stain fungus which begins to grow in the tree’s tissues as soon as a beetle bores into the bark. The growing fungus further disrupts the flow of water and nutrients within the tree. Immature beetles feed on this fungus. The eggs and larvae complete development by June and July and the newest generations of western pine beetles continue to attack trees until September.
Mountain Pine Beetle
Up to 20 generations of mountain pine beetle are produced each year in some areas. Mountain pine beetles (MPB) are similar size and shape to western pine beetle, and also carry the blue-stain fungus. Adult MPB emerge in June to attack new trees. They create vertical galleries which closely follow the grain of the wood. There is a short crook at the bottom of each gallery, resembling a ‘J’. This is the primary difference between MPB and western pine beetle. This difference is discernable when a hatchet is used to carefully remove a portion of bark. Removing bark from healthy trees is not recommended.
The North Okanagan is an ideal environment; up to three generations of beetles hatch each year to attack new trees. This happens when the last adult beetles emerge in September and October. These beetles overwinter and lay eggs as soon as the weather warms in spring. Overwintering beetles, eggs, larvae and pupae can withstand temperatures as low as -38°C.
Signs of Pine Beetle Infestation
If you have pine trees on your property, please check periodically for the following signs of beetle attack:
| |
Click to enlarge |
Pitch tubes: Surrounding the hole where a pine beetle has bored into the bark, ‘pitch tubes’ are the tree’s attempt to rid itself of the beetle. Pitch tubes appear on the trunk and may be white, clear, pinkish, or brown. You may see beetles caught in the resin when the tree has successfully pushed the beetle out. |
 |
Sawdust or frass: Fine sawdust at the base of the tree or near the bore holes in bark crevices of successful beetle attacks. |
 |
Discoloured Needles: Green, healthy needles will turn yellow, orange, bright red and then brown as the tree weakens and dies as a result of successful beetle attack. Discolouring occurs the year after the attack and by the time the needles are red, the beetles have already matured and left the tree. The tree bark should still be examined to confirm that bark beetles are still present. This will determine which action is needed to reduce risk to property and nearby healthy trees. |
 |
Bark: As the pine beetle population in a specific tree increases, portions of the bark may be removed by feeding woodpeckers.
|
 |
Galleries: Mountain pine beetles create vertical galleries which closely follow the wood grain, with a short crook or bend at the bottom, resembling a ‘J’. Western pine beetles create sinuous, meandering galleries which form complex networks. To positively identify the bark beetle species, carefully remove a portion of bark with a hatchet to see the galleries. |
 |
Blue-stain fungus: Both western pine beetle and mountain pine beetle adults carry blue-stain fungus and infect the tree as soon as the beetles begin feeding on the inner bark. Beetle larvae and pupae feed on the fungus as they develop and mature. The fungus plugs the tree’s tissues which transport food and water between the tree’s roots and foliage. The blue-grey colour is easily visible when a portion of bark is carefully removed with a hatchet. |
 |
Prevention:
There is no guaranteed prevention against pine beetle attack, but there are options that have shown to be useful in slowing the spread of the beetles in our area.
- Monitoring: Monitoring is the first line of defense against the pine beetle epidemic. Learn how to identify pine beetle attack, or hire a professional to help monitor your trees periodically. Western pine beetle can attack any time from April to October, while mountain pine beetle attack late June to October. If you find early signs of attack, hire a professional to help you decide whether to treat or dispose of the tree.
- Remove and dispose infested trees: Before considering how to prevent future problems, first identify and properly dispose of infected trees. See Disposing Infested Wood.
- Keep your trees healthy: Trees that have been topped, poorly pruned, injured, buried under fill, root damaged or are suffering from drought-stress are more susceptible to beetle attack. Never top your trees and avoid pruning live branches during the spring and summer growing season, as beetles can be attracted to pruning wounds. Watering your trees can help them form ‘pitch tubes’ to push out invading beetles. Be careful to avoid over-watering, as this can stress trees and make them more vulnerable to attack. Avoid nitrogen fertilizers, as they also may actually make trees more vulnerable to attack. If you do choose to fertilize, use small amounts of well-rotted compost. Avoid placing fresh bark or wood chips near your pine trees, as this can attract beetles to your property.
- Consider thinning out larger pine stands: Research suggests thinning can help prevent beetle attack in forested stands. As a general guideline, thin trees so that the crowns do not touch. Consult a professional to help you determine the most appropriate tree density for your property, and to help you remove trees safely.
- Pheromone Repellents: When attacking a new tree, mature mountain pine beetles (MPB) release an aggregation pheromone, a chemical scent that attracts other beetles to that tree and to overcome the tree’s natural defenses (pitch tube formation). Once the tree is full of MPB, the beetles release another kind of pheromone called verbenone, to discourage more beetles from attacking the tree. Verbenone pouches are attached to trees to discourage MPB from landing there. Research suggests that verbenone pouches are most effective when beetle populations are still low. Verbenone pouches are available at garden centres, hardware stores and from tree care professionals.
- Wrapping: This method involves wrapping the first nine metres (30 feet) of a tree’s trunk with plastic mesh window screening to create a physical barrier between the trunk and the beetle. This method is most commonly used on high-value and heritage trees. The lower branches are first pruned so the stem is clear up to 9m, though large branches can also be wrapped. Trees are wrapped vertically to reduce the chance of gaps, since beetles will gain entrance through any gaps in the seams. After the screen has been stapled to the bark, leaving some extra room for tree growth, the seam is sealed with a silicone caulking compound. This is a difficult and potentially dangerous procedure that should be completed by professionals.
- Diversified Landscape: Change your landscape plan to include other types of trees. A diversified landscape is less susceptible to epidemic attack. Replacing beetle attacked trees will help stabilize the soil and help maintain water quality. Consult your local garden centre or a tree professional for appropriate alternatives to the pine trees most susceptible to attack.
Managing Infested Trees:
- Removal and Disposal: Since each beetle infested tree contains enough beetle brood to infest between three and eight healthy trees, it is extremely important to remove and dispose of infested trees prior to March 31, when mature beetles begin to emerge and fly to new sites.
- Beetle infested trees cannot be used for firewood, transported or stored for any length of time unless they are debarked. Infested bark should be chipped or buried to ensure adults and larvae are destroyed.
- Pesticides: Other than Verbenone pouches, there are no chemical pesticides registered for home use on pine beetles. Chemical pesticides must be applied by certified commercial applicators using appropriate equipment.
Disposing Infested Wood:
- Burning: For information on burning practices and local bylaws, please contact the Regional District of North Okanagan at 550-3700.
Beetle infested trees cannot be used for firewood, transported or stored for any length of time unless they are debarked. Infested bark should be chipped or buried to ensure beetle brood are destroyed.
- Landfill: All Recycling and Disposal Facilities within the Regional District of North Okanagan accept beetle infested yard waste and beetle infested wood. Yard waste includes wood debris less than 20cm in diameter. The tipping fee for yard waste is $0.02 per kilogram. The tipping fee for logs and stumps greater than 20cm in diameter, and less than 150cm in length is $0.035 per kilogram. Free disposal of yard waste from March 15 to April 30.
Click here for Recycling and Disposal Facility locations and hours.
- Selling: Landowners wishing to sell their timber should contact a log buyer or forestry professional for advice. Look in the Yellow Pages under “Logging Companies & Contractors”, “Logging Services”, and “Tree Service”. Any wood transported from private land requires a timbermark which is available free of charge from the BC Ministry of Forests. Download the one-page application form and fax to:
Links:
Western pine beetle:
Mountain pine beetle:
Currently there is no funding available through the Regional District of North Okanagan for Pine Beetle control. Should you have any questions about the Pine Beetle in this area, please refer to the links above.
|
|
)
)
)
)
)
)
