tortoise beetle

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of several small beetles of the subfamily Cassidinae, shaped somewhat like a tortoise and having soft, fleshy larvae that eat the leaves of trees.

Century Dictionary and Cyclopedia

1. n. A leaf-beetle of the family Cassididæ: so called from the projecting elytra and prothorax, which suggest the carapace of a tortoise. This resemblance is heightened in some cases by the coloration. Several species in the United States feed upon the sweet potato, as Deloyala clavata. See also cuts under Cassida, Coptocycla, Deloyala, and Physonota.

GNU Webster's 1913

1. n. (Zoöl.) any one of numerous species of small tortoise-shaped beetles. Many of them have a brilliant metallic luster. The larvæ feed upon the leaves of various plants, and protect themselves beneath a mass of dried excrement held over the back by means of the caudal spines. The golden tortoise beetle (Cassida aurichalcea) is found on the morning-glory vine and allied plants.