Notes on balsam woolly adelgid, Adelges piceae (Ratzeburg, 1844) (Hemiptera: Adelgidae), range expansion in Idaho, Montana and Utah

Abstract

The earliest reports of balsam woolly adelgid, Adelges piceae (Ratzeburg, 1844), in North America occurred in Maine in 1908 and California in 1928 (Kotinsky 1916, Annand 1928). By the late 1960s, this non-native pest was common throughout the ranges of native true fi r species, Abies spp. (Pinaceae) in the eastern United States and along the Pacifi c Northwest coast. In the interior west, Livingston et al. (2000) detected balsam woolly adelgid in Idaho in 1983, then observed declining health and death of subalpine fir, A. lasiocarpa (Hooker) Nuttall, over the next 15 years, primarily in north-central Idaho. This seemingly slow invasion from the west coast to Idaho may be due, in part, to diffi culty detecting an insect less than one millimeter in size. Another factor may have been a geographic barrier, the Columbia Basin, slowing the west to eastward dispersal between viable host trees.