The Collaborative International Dictionary of English v.0.48:

Inchworm \Inch"worm`\, n. (Zool.)
   The larva of any geometrid moth. It progresses forward by
   first bringing the rear end of the body forward, forming a
   loop, then moving the front part of the body; called also
   measuring worm, measuringworm, spanner, and looper.
   See Geometrid.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Looper \Loop"er\ (l[=oo]p"[~e]r), n.
   1. An instrument, as a bodkin, for forming a loop in yarn, a
      cord, etc.
      [1913 Webster]

   2. (Zool.) The larva of any species of geometrid moths. See
      Geometrid.
      [1913 Webster]

WordNet (r) 3.0 (2006):

looper
    n 1: small hairless caterpillar having legs on only its front
         and rear segments; mostly larvae of moths of the family
         Geometridae [syn: measuring worm, inchworm, looper]