See link and video below to learn how to collect surface-floating pupal exuviae (SFPE): Use of Chironomidae (Diptera) Surface-Floating Pupal Exuviae as a Rapid Bioassessment Protocol for Water Bodies video: https://www.facebook.com/114778358598205/videos/570730220305/ Map of Minnesota showing approximate locations of all SLICE lakes: http://www.dnr.state.mn.us/fisheries/slice/sentinel.html