The adult Japanese Beetles should begin hatching in the next week or so. Weather station at Reed City has measured 1002 degree days (using base 50) for the year. Adult Japanese Beetles usually emerge to breed and feed after an accumulation of 950 degree days (base 50). This information can be found on the MSU Enviroweather web site located here: Homepage - MSU - Enviroweather the Degree Day Tracker can be found here: GDD Tracker 4.0 - Turf Pest Management Tracking and Alerts with Growing Degree Day Models for Michigan, Illinois, Indiana and Ohio - Project initiated by Michigan State University (msu.edu)

Information on the Japanese Beetle can be found here: Japanese beetle - Integrated Pest Management (msu.edu)

Thank you for your question and have a great gardening experience.