\Web"form`\, n. (Zo["o]l.)
Any one of various species of moths whose gregarious larv[ae]
eat the leaves of trees, and construct a large web to which
they retreat when not feeding.
Note: The most destructive webworms belong to the family
      {Bombycid[ae]}, as the fall webworm ({Hyphantria
      textor}), which feeds on various fruit and forest
      trees, and the common tent caterpillar, which feeds on
      various fruit trees (see {Tent caterpillar}, under
      {Tent}.) The grapevine webworm is the larva of a
      geometrid moth (see {Vine inchworm}, under {Vine}).