\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}).