SUPERFAMILY IV. PHYTOPHAGA Plant-feeding beetles with the antennae generally simple, less often pectinate or serrate: tarsi apparently 4-jointed, the 4th joint minute and concealed by the 3rd joint. Larvae eruciform with short or rudimentary legs. The Chrysomelidae or leaf beetles (fig. 15) number about 2o,000 described species, being the second largest family of Cole optera. These insects are usually bare and shining often with me tallic colours, the antennae are of moderate length and are not embraced by the eyes around their points of origin from the head. Included in this family are such well known insects as the Colorado potato beetle and the asparagus beetle. In all cases the larvae and beetles feed on the leaves and other parts of plants : in the elongate metallic species of Donacia the larvae live sub merged in the roots and stems of water plants.
The Cerambycidae or longicorn beetles (fig. 16) are closely allied to the above family but are more rarely metallic and usually somewhat pubescent, elongate insects with the bases of the an tennae more or less embraced by the eyes. The antennae are frequently elongate and slender, usually longest in the males and sometimes several times longer than the whole insect. They are mainly denizens of woods and forests, and about 13,000 species are known. Their larvae have soft fleshy bodies with a hard head and jaws, broad prothorax and very much reduced legs : they tunnel into the wood of trees and are often destructive. Some species live several years as larvae.
The other family of Phytophaga is the Bruchidae (or Laridae) whose larvae live in seeds, especially dried peas, beans, etc.