Larvae of Lepidoptera and Tenthredinidae (sawflies) not only have three pairs of thoracic feet, like all insects, but also several abdominal segments have a pair of appendage that look like feet, and have the same function. Usually they have a row or circle of crochets at their tip. A less formal term for prolegs is abdominal feet.

Epermenia chaerophyllella: larva with thoracic feet and prolegs