This RAPID project is a study of the changes in volatile organic carbon (VOC) emissions from Lodgepole pine trees (Pinus contorta var. latifolia) as a result of the rapidly expanding infestation of pine bark beetles (Dendroctonus ponderosae) in the Western United States. Lodgepole pine is a widespread and abundant species in Western montane forests. Preliminary measurements of VOC emissions from infested and non-infested trees have shown different emission patterns of monoterpenes, which are important precursors for secondary organic aerosol (SOA) formation. Because the various monoterpenes differ in their SOA formation potential, changes in their patterns of emission may have far-reaching effects on visibility and radiative forcing of climate on a regional scale. There is some urgency to this project because the beetle infestation is underway and spreading rapidly. It offers a unique, early opportunity to observe and document impacts on the atmosphere of an insect infestation of the type that is projected to become increasingly frequent and severe as the climate warms. Sampling is carried out in consultation with and with the approval of the USDA Forest Service, which has issued a special use permit for field work in the Routt-Medicine Bow National Forest. This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).