Peak alfalfa weevil feeding damage occurs between 325 and 575 heat units (based on accumulation of heat units from January 1 with a base of 48°F). All monitored locations are now in or close to this range except Ashtabula. We recommend alfalfa weevil scouting as regular part of your program. For more details on alfalfa weevil scouting and thresholds please see our April 13 article https://agcrops.osu.edu/newsletter/corn-newsletter/2020-09/alfalfa-weevil-%E2%80%93-it%E2%80%99s-closer-you-think
Accumulated growing degree days (base 48°F sine calculation method) for January 1-May 17, 2020 at several CFAES Ag Weather System (https://www.oardc.ohio-state.edu/weather1/) locations and additional NOAA stations around Ohio.