Initial emergence of EAB adults from trees is anticipated after accumulation of 450 degree days (base 50 degrees Fahrenheit). A degree day is a measure of accumulated heat and in this case provides a means to track how much development time EAB immature stages (within trees) have had.

Degree day accumulations are used to track development of other insects as well, including a common insect in the Midwest - the European corn borer. European corn borer degree days are calculated on the same scale as EAB (base 50 degrees F) and a map for the Minnesota / Wisconsin area is available online at:

http://www.soils.wisc.edu/wimnext/corn/euroborer.html

When an area reaches 450 degree days for European corn borer, then initial EAB flight can also be anticipated.