To minimize moisture build up, lids had a 5 cm diameter hole cut in them and fine mesh (150 mm, The Cary Company, Addison, IL) affixed over the hole using hot glue. Cups with collected blueberry fruit and flies were placed in an environmental chamber at 25 C, 75% RH, and a 16:8 L:D cycle. After 24 h the number of dead, moribund, or alive flies was recorded.