Spruce Beetle 1 Winter Mortality Resulting from Record Low Temperatures in Arizona

Abstract

During the week of January 1, 1971, a cold period with a record low temperature of −40°C (−40°F) occurred near an area supporting high spruce beetle populations on the Fort Apache Indian Reservation, Arizona. This resulted in 88% spruce beetle larval mortality above the snow level in sampled standing trees. Below the snow level, mortality of larvae and hibernating adults was 15 and 28%, respectively. Parasites, predators, and other associated species incurred lower mortality.