[Illustration: Fig. 136—A, Larva of _Euchroma goliath_ (after Schiödte); B, imago of _Melanophila decostigma_. Europe.] The larvae (Fig. 136, A) find nourishment in living vegetable matter, the rule being that they form galleries in or under the {262}bark of trees and bushes, or in roots thereof; some inhabit the stems of herbaceous plants and one or two of the smaller forms have been discovered to live in the parenchyma of leaves. A few are said to inhabit dead wood, and in Australia species of _Ethon_ dwell in galls on various plants. Buprestid larvae are of very remarkable shape, the small head being almost entirely withdrawn into the very broad thorax, while the abdomen is slender.[135] A few, however, depart from this shape, and have the thoracic region but little or not at all broader than the other parts. The larvae of _Julodis_—a genus that inhabits desert or arid regions—are covered with hair; they have a great development of the mandibles; it is believed that they are of subterranean habits, and that the mandibles are used for burrowing in the earth. Only the newly hatched larva is, however, known. SERIES IV. HETEROMERA. _Tarsi of the front and middle legs with five, those of the hind legs with four, joints._ This series consists of some 14,000 or 15,000 species. Twelve or more families are recognised in it, but the majority of the species are placed in the one great family, Tenebrionidae. The number of visible ventral segments is nearly always five. Several of the families of the series are of doubtful validity; indeed beyond that of Tenebrionidae the taxonomy of this series is scarcely more than a convention. The larvae may be considered as belonging to three classes; one in which the body is cylindrical and smooth and the integument harder than usual in larvae; a second in which it is softer, and frequently possesses more or less distinct pseudopods, in addition to the six thoracic legs; and a third group in which hypermetamorphosis prevails, the young larvae being the creatures long known as Triungulins, and living temporarily on the bodies of other Insects, so that they were formerly supposed to be parasites.