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Pine forests across the United States, Canada, and Mexico are being challenged by a biological threat: a massive infestation of the pine bark beetle. Experts believe it is the largest insect infestation recorded until now. Millions and millions of evergreen trees are slowly dying. Ponderosa, scotch and lodgepole pine trees seem to be the most susceptible.
Pine forests affected by beetle infestation have been found in the US in areas with elevations of 2,000 to 6,000 feet (600 to 1800 m). In Northern Mexico, infestations have been observed in forests above 8,000 feet (2,400m), and in Canada in forests or urban settings below 1,000 feet (300 m).
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What is the Pine Bark Beetle?
Dendroctonus ponderosa is the scientific name of this insect that is destroying North American majestic pine forests. The insect is commonly known by names such as the Pine Bark Beetle, the Black Hills Beetle, the Rocky Mountain Pine Beetle, or simply the Bark Beetle. This insect is native to North America. During the last few years, infestation by the pine bark beetle has been massive in both urban and wild areas.
The insect starts to act on unhealthy trees. Any tree that has some degree of damage due to drought, age, wind, or lightning may be subjected to infestation. Healthy trees may come under attack once there is a significant number of infected trees in an area. Unfortunately, the pine bark beetle infestation is deadly. The first sign of trouble on the trees is the appearance of an orange colorization.
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Why is the Pine Bark Beetle Infestation so Massive Today?
During the last few years, there has been a combination of factors that have allowed the bark beetle to thrive as never before. First, there have been exceptionally warm winters. The beetle is controlled if the winter is cold enough. Temperatures below -20F (-27C), which are sustained for several days, are the only way to kill the beetle. Since this has not occurred in the last few years, the insect is growing uncontrollably.
In addition, sustained drought over the last few years has debilitated many pine trees, which makes them a fertile ground for beetle infestation. The successful control of fires also conspires against pine trees. Fires were a natural way to control beetle growth: if there are less fire, there is more beetle growth.
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What Can be Done?
Prevention is the key to stop pine bark infestation. There are a few things a landowner can do to prevent the infestation. Anything that prevents tree damage will prevent the bark beetle attack. G. Keith Douce, Professor of Entomology, of The University of Georgia Cooperative Extension Service recommends the following actions:
- Vigorous tree growth should be encouraged. Beetle attacks increase with age and slow diameter growth. Shorter pine rotations are encouraged.
- Harvest, thinning, and pruning operations should be delayed until winter.
- Storm or lightning-damaged pine trees should be removed as quickly as possible. Damaged pines are ideal sites for bark beetle infestations.
- Mechanical tree damage should be minimized. Tree damage encourages bark beetle infestations. Building barricades around trees to prevent mechanical damage by equipment in yard and landscape environments will also help.
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Bark Beetles Kill Millions of Acres of Trees in West - NYTimes.com www.nytimes.com/2008/11/18/science/18trees.html
Bark and Wood Boring Beetles of the World (http://www.barkbeetles.org/)
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wetape at. sxc.hu (http://www.sxc.hu/photo/1240637)
kamila turton at www.sxc.hu (http://www.sxc.hu/photo/1208521)