end. This acts like a snorkel, allowing the larva to breathe air while submerged. The siphon is usually about as long as the maggot's body (20 mm 0 abbr=on when mature), but can be extended up to about 150 mm 0 abbr=on. This organ gives the larva its common name.

The most commonly encountered rat-tailed maggot is the larva of the drone fly, Eristalis tenax. It lives in stagnant, oxygen-deprived water, with a high organic content.