CATERPILLAR, the popular name of the larva of various insects, particularly of butterflies and moths (see Lepidoptera, Hexapoda, Metamorphosis). The word appears first in the form caterpyl (Promptorium Parvulorum, about the middle of the 15th century). This may be the original form, with the addition of -ar or -er; if so, it represents the O. Fr. chatepelose or chatepeleuse, i.e. "hairy-cat" (chat, cat, and pelouse, hairy, Lat. pilosus), a name applied to the hairy caterpillar, and also according to Cotgrave to a weevil. The use of "cat" in this connexion is paralleled by the Swiss name for a caterpillar, teufelskatz, and the popular English name for the blossom of the willow, "catkin," somewhat resembling a caterpillar (cf. "palmer"); the modern French is chenille, Latin canicula, a little dog. The termination of the word seems to have been early connected with "piller," a robber, plunderer from the destructive habits of the larva, cf. Joel i. 4 - "That which the palmer-worm hath left, hath the locust eaten." The spelling "caterpillar," a 17th century corruption, has been the usual form since Johnson.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)