High elevation emerging geometrid insect pests in the southwestern United States

Since 1996, native geometrids have been responsible for 4 separate outbreaks at high elevations in the southwestern United States. Historically three of these insects were not known to cause damage. Speculation that climate change may be a factor in these outbreaks has led to the current study. Specimens taken at two of the outbreaks have both been identified as Nepytia janetae; a third geometrid has been identified as Enypia griseata. Adults of N. janetae were described in 1967 from collections made in Arizona and New Mexico. The larvae of the two insects identified as Nepytia janetae have been observed to have different feeding patterns, different elevational ranges and different host ranges in addition to physical differences. The third outbreak by a geometrid was found in a 2007 in Arizona. Significant tree mortality has been associated with heavy defoliation by the geometrids alone or in conjunction with secondary agents such as bark beetles and other defoliators.