Figure 1. Example of a map showing the accumulation of 50 degree days (base 50°F) by location in Michigan and surrounding states. Mapping was based on 30-year average temperatures recorded at 92 different weather stations across the illustrated region. The pest list and maps of degree day accumulation (from 50 to 2000 DD 50 by 50 DD intervals) will soon be available on the internet at http://www.fs.fed.us/spfo/.