In addition to the chironomid larvae, oligochaetes , and the small clam Pisidium , another major component of the profundal zone of lakes is the phantom midge Chaoborus . The larvae are called phantom larvae because of their transparency. They are unique in that their enlarged antennae have been modified for capturing prey such as insect larvae and small crustaceans. They are the only ins ects frequently found in the limnetic area of lakes. Adults do not feed, but their synchronized emergences may create severe nuisance problems around large lakes because adults are highly attracted to lights.
Life cycles are univoltine to multivoltine, de pending on species, climate, and habitat.
Most larvae can be identified to species. The larvae can develop to the fourth instar in six to eight weeks. The first and second instars are always limnetic and positively phototactic, and they develop rapidly in a few weeks. The fourth instar of many species of Chaoborus undergoes strong diurnal vertical migrations. Migration is influenced in part by oxygen tension of the water ne ar the sediments.