Estimation of the weevil instars present in the field can be calculated using degree-days. Alfalfa weevil development increases at a nearly constant rate as the temperature rises above 48°F (9°C.). The amount of warm weather required for weevil larvae to complete development is measured in units of degree-days. View 2011 Alfalfa Weevil Degree Days.
Sunflower stem weevil pupation, adult formation and emergence in the field can be predicted using accumulated degree-days. The stem weevil development increases at a nearly constant rate as the temperature rises above 41°F (5°C.). View 2010 Sunflower Stem Weevil Degree Days.