MEASURING WORM, INCH WORM, LOOPER, or SPAN-WORM, a caterpillar of any species of moth of the superfamily Geosnetrida, The creatures are characterized by the presence of only two pairs of abdominal legs, one upon the ninth, the other upon the anal segment, and by their peculiar form of loco motion, the rear of the body being brought forward toward the front legs and the body forming a loop at right angles to the surface upon which the insects walk. Nearly all the numerous species feed upon foliage, a few upon seeds in which they bore. Some are considered serious pests in orchards and upon shade trees; for instance, the canker worms (see APPLE, Insects), the lime-tree moth (Hybernia tiliaria), and Cymatophora pampinaria, which sometimes devastates cranberry plantations. The duration of the larva state is variable; from their great voracity they grow rapidly and shed their skins several times before attaining maturity; when arrived at this state they seek some sheltered spot in which to undergo the change to pupa form, some clinging to the lower surfaces of leaves while others bury themselves in the earth, those remaining in the air suspending them selves in various ways by means of their silky secretions, others enclosing themselves in silky cocoons. Those burying themselves also build cocoons around them, but many of these only line their cavity with enough silken threads to keep the wall from falling in. One of the Euro pean species, Fidonia Plunsistaria, is distin guished by curious feathery antenna'. The cater
pillars of this species are very injurious to fruit trees, especially those of the European magpie moth, Abraxas grossulariata, which inhabit gooseberry bushes, often entirely stripping them of their foliage. The caterpillar of the Ameri can canker worm moth, A. nisopteryx pone taria, also belongs to this species of worm, the eggs being hatched in the spring; when grown they are about an inch long and of various colors, and are also dangerous to orchards. Most of the species, however, are of small economic importance. The caterpillars usually resemble twigs when at rest, their protective coloring and their attitudes serving to deceive their enemies. The caterpillars of a few species of the owlet moths, family Noctuidce, walk in this way, since they also lack prolegs upon the middle abdominal segments. They are not, how ever, considered true measuring worms. The geometrid moths are usually of small size and inconspicuous but delicate and beautiful colora tion. Consult Holland, The Moth Book> (New York 1903) ; and Packard's
of the Geometridie,> with colored plates, published by the United States Geological Survey (Washing ton 1876);