the dried insect-skins hanging in old cobwebs.

[Illustration: FIG. 16.--_Clerus apiarus_ (Hive Beetle). Europe.]

[Illustration: FIG. 17.--_Dermestes lardarius_ (Bacon Beetle).]

STERNOXIA.--This is an important tribe of beetles, including families
with four malpighian tubes and only five or six abdominal sterna,
while in the thorax there is a backwardly directed process of the
prosternum that fits into a mesosternal cavity. The larvae are
elongate and worm-like, with short legs but often with hard strong
cuticle.

[Illustration: FIG. 18.--A, Wireworm; B, pupa of Click Beetle; C,
adult Click Beetle (_Agriotes lineatum_).]

The _Elateridae_ or click beetles (fig. 18) have the prosternal
process just mentioned, capable of movement in and out of the
mesosternal cavity, the beetles being thus enabled to leap into the
air, hence their popular name of "click-beetles" or "skip-jacks." The
prothorax is convex in front, and is usually drawn out behind into a
prominent process on either side, while the elytra are elongate and
tapering. Many of the tropical American _Elateridae_ emit light from
the spots on the prothorax and an area beneath the base of the
abdomen; these are "fireflies" (see above). The larvae of _Elateridae_
are elongate, worm-like grubs, with narrow bodies, very firm cuticle,
short legs, and a distinct anal proleg. They are admirably adapted for
moving through the soil, where some of them live on decaying organic
matter, while others are predaceous. Several of the elaterid larvae,
however, gnaw roots and are highly destructive to farm crops. These
are the well-known "wire-worms" (q.v.).

[Illustration: FIG. 19.--_Catoxantha bicolor_. Java.]

The _Buprestidae_ are distinguished from the _Elateridae_ by the
immobility of the prosternal process in the mesosternal cavity and by
the absence of the lateral processes at the hind corners of the
prothorax. Many tropical _Buprestidae_ are of large size (fig. 19),
and exhibit magnificent metallic colours; their elytra are used as
ornaments in human dress. The larvae are remarkable for their small
head, very broad thorax, with reduced legs, and narrow elongate
abdomen. They feed by burrowing in the roots and stems of plants.

BOSTRYCHOIDEA.--This tribe is distinguished from the Malacoderma and
allied groups by the mesothoracic epimera not bounding the coxal
cavities of the intermediate legs.