MEASURING WORM. Any one of the larv:e of the lepidopterous superfamily fleoniet rida., also called humors. The group is a very extensive one and consists of fragile moths with COMparativvly large wings. The eaterpillars a•e long and slender, with only one pair of abdominal feet phieed upon the ninth segment of the body. 'There is also an anal pair of feet which function as claspers. 'Flue measuring worms walk by mov ing these two pairs of feet up to the thoracic legs, so that the body forms. a large loop, giving the insect the appearance of measuring the sur face upon which it is walking. It is this habit which has given the popular names 'Ioopers.' 'inchworms,' etc. (see IiKOMETRID :\10T11), and schnitilie name Geometrid:c to the insects of this group. Measuring, worms feed upon the leaves I if plant,, with the except hm tif a few which bore into seeds. They cure usually protec tively colored so as to resemble twigs, and Ihey have the attitude when at rest of holding the body still' and erect at an angle from the main stem of the plant, so that they almost perfectly resemble twigs. The individuals of the same species vary in color during life. and with some species there is a well-marked dimorphistn. In sloe species the dimorphism is potential. and the future color is settled by some condition occurring during the early life of the larva. Poulton has made a careful study of the atti tudes and colors of these larvae, and rates the value of their protecting influence at a very high point. In one variable English species he
states that the dark tint is due to pigment in the skin or immediately below it and the green color to a layer of fat between the hypodertnis and the superficial muscles. In some geometrids the adult females are wingless. A marked ex ample of this group is seen in the canker-worm moths of the 'United States. (See CANKER WoRm.) The winter moth (Cheiniatobia brawl ), a species which is common and widespread in Europe and North America, has also a wing less female. One of the currant-worms common to Europe and North America (Eufitehia ri bearia) is a member of this group in which the female is fully winged.
Certain moths of the noctuine series exist, whose lack certain of the middle prologs, and which therefore walk in a looping or meas uring manner, but these are not true measuring worms. The cotton caterpillar xylina) is an example.
Consult: Edwards, Standard Natural History, vol. ii. (Boston, 1884); Comstock, Manual for the Study of Insects (Ithaca, 1895) : Sharp, Cambridge Natural History, vol. vi. (London, 1899) ; Packard, "A Monograph of the Geomet rid Moths or Phalamithe of the United States," in Hayden's Annual Report of the United Geological Surrey, vol. x. ( Washington, 1870).