Students frequently observe phantom midge larvae (Chaoborus sp.) under microscopes in the lab. Phantom midge larvae are also known as glassworms because of their transparent bodies.Phantom midges can be quickly identified by their noticeable pair of black kidney-shaped structures in the front and the back of their bodies. These are air sacs that allow the organism to move within the water column. Chaoborus species also have an anal fan-like structure. Species can be identified by counting the rays of this fan.
Chaoborus are voracious predators and prey on many of the zooplankton species present in Mac's Pond, including cladocerans, copepods, and rotifers.
During the day, Chaoborus generally stay near the bottom of lakes. They exhibit diel vertical migration and migrate to surface waters during the night to feed on smaller zooplankton. In the first molts of a Chaoborus life, they are planktonic and drift more than they do later in their larval stages.
Chaoborus are pollution tolerant, and can survive in anoxic conditions often found at the bottom of lakes