We arrive now at the tribe of Silphales, which are still more useful to man than the Dung Beetles (Scarabæidæ), since many of them disencumber the soil of the carcases of animals in a state of putrefaction. The most remarkable insects of this tribe are the Histers, the Silphas, properly so called, and the Necrophora.
Fig. 450.—Lucanus bellicosus.
The Histers are small insects, to be recognised by their body being almost round, smooth, and shining, with the elytra marked with striæ, and their mandibles pretty well developed. They attain to a length of about a fifth of an inch. The Silphæ, thus named on account of their broad and rounded form, are of a large size (about half to three-quarters of an inch), of a dark colour, and exhale a sickly odour. When seized, they disgorge a blackish liquid. They introduce themselves under the skin of the carcases of animals, and devour their flesh to the very bone. The larvæ, flat and serrated, live like the adults, in carrion. The commonest species is the Silpha obscura, of an intense black, delicately dotted. Two species found in England and in the environs of Paris, Silpha quadripunctata and the Silpha thoracica, climb trees and attack caterpillars. It appears to be certain that the larva of the Silpha obscura does a great deal of damage to beet-root, whose leaves it devours. The Necrodes come very near to the Silphæ. They are distinguished from them by having the hind legs larger. Only one, Necrodes littoralis, occurs in England. [Fig. 459] represents the Necrodes lacrymosa, from Australia. The Necrophori, or Grave-diggers, are honest undertakers, who carefully bury carcases left on the soil. As soon as they smell a field-mouse, a mole, or a fish in a state of decomposition, they come by troops to bury it, getting under the carcase, hollowing out the ground with their legs, and projecting the rubbish they dig out in all directions. Little by little the carcase sinks; at the end of twenty-four hours it has generally disappeared into a hole five inches in depth, but the Necrophori sink it still lower—as far as from seven to ten inches below the surface. They then mount it, cast the earth down into the grave so as to fill it, and the females lay their eggs in the tomb, where the larvæ will find an abundance of food. When the ground is too hard to be dug, the Necrophori push the carcase further, till they find permeable soil. A mole has been run through with a stick, or else tied by a string, to see how the Necrophori would get over the difficulty. They scooped out the soil underneath the stick, and cut through the string, and the mole was buried in spite of the obstacles. [Fig. 460] represents a troop of Necrophori burying a small rat.
Fig. 451.—Dorcus Titan.
| Fig. 452.—Syndesus cornutus. | Fig. 453.—Chiasognathus Grantii. |
| Fig. 454.—Hister rugosus. | Fig. 455.—Silpha quadripunctata. | Fig. 456.—Silpha thoracica. |