Changes in the caloric content of the phantom midge,Chaoborus punctipenniswere compared in lakes of 8 m and 26 m depth. Organisms were collected monthly from March through November. Mean caloric content was 6355 and 4534 cal/g ash-free weight in the shallow and deep lake, respectively. Variation in migration distance of the organisms between the two lakes was suggested as influencing the pronounced variation in caloric content.