The other divisions of Malacodermidae—Lycides, Drilides, Telephorides—also have predaceous, carnivorous larvae. All these groups are extensive. Though much neglected by collectors and naturalists, some 1500 species of the family Malacodermidae have been detected. We have about 50 in Britain, and many of them are amongst the most widely distributed and abundant of our native Insects. Thus, however near they may be to the primitive condition of Coleoptera, it is highly probable that they will continue to exist alongside of the primitive Cockroaches and Aptera, long after the more highly endowed forms of Insect-life have been extinguished wholesale by the operations of mankind on the face of the earth.
Fig. 130—Malachius aeneus. Britain. A, Larva (after Perris); B, female imago.
Fam. 55. Melyridae (or Malachiidae).—Six visible and moveable ventral abdominal segments; the basal part more or less distinctly co-adapted with the coxae. These Insects are extremely numerous, but have been very little studied. In many works they are classified with Malacodermidae, but were correctly separated by Leconte and Horn, and this view is also taken by Dr. Verhoeff, the latest investigator. The smaller number of visible ventral segments appears to be due to a change at the base correlative with an adaptation between the base of the abdomen and the hind coxae. The characters are singularly parallel with those of Silphidae; but in Melyridae the antennae are filiform or serrate, not clavate. The habits in the two families are different, as the Melyridae are frequenters of flowers. Many of the Melyridae have the integument soft, but in the forms placed at the end of the family—e.g. Zygia—they are much firmer. Thus these Insects establish a transition from the Malacodermidae to ordinary Coleoptera. Although the imagos are believed to consume some products of the flowers they frequent, yet very little is really known, and it is not improbable that they are to some extent carnivorous. This is the case with the larvae that are known (Fig. 130, larva of Malachius aeneus). These are said by Perris to bear a great resemblance to those of the genus Telephorus, belonging to the Malacodermidae.
Fam. 56. Cleridae.—Tarsi five-jointed; but the basal joint of the posterior very indistinct, usually very small above, and closely united with the second by an oblique splice; the apices of joints two to four usually prolonged as membranous flaps; anterior coxae prominent, usually contiguous, rather large, but their cavities not prolonged externally; labial palpi usually with large hatchet-shaped terminal joint; ventral segments five or six, very mobile. The Cleridae are very varied in form and colours; the antennae are usually more or less clubbed at the tip, and not at all serrate, but in Cylidrus and a few others they are not clubbed, and in Cylidrus have seven flattened joints. The student should be very cautious in deciding as to the number of joints in the feet in this family, as the small basal joint is often scarcely distinguishable, owing to the obliteration of its suture with the second joint. The little Alpine Laricobius has the anterior coxal cavities prolonged externally, and the coxae receive the femora to some extent, so that it connects Cleridae and Derodontidae. The Cleridae are predaceous, and their larvae are very active; they are specially fond of wood-boring Insects; that of Tillus elongatus (Fig. 131) enters the burrows of Ptilinus pectinicornis in search of the larva. The members of the group Corynetides frequent animal matter, carcases, bones, etc., and, it is said, feed thereon, but Perris's recent investigations[[130]] make it probable that the larvae really eat the innumerable Dipterous larvae found in such refuse; it is also said that the larvae of Cleridae spin cocoons for their metamorphosis; but Perris has also shown that the larvae of Necrobia ruficollis really use the puparia formed by Diptera. Some of the species of Necrobia have been spread by commercial intercourse, and N. rufipes appears to be now one of the most cosmopolitan of Insects. The beautifully coloured Corynetes coeruleus is often found in our houses, and is useful, as it destroys the death-watches (Anobium) that are sometimes very injurious. Trichodes apiarius, a very lively-coloured red and blue beetle, destroys the larvae of the honey-bee, and Lampert has reared Trichodes alvearius from the nests of Chalicodoma muraria, a mason-bee; he records that one of its larvae, after being full grown, remained twenty-two months quiescent and then transformed to a pupa. Still more remarkable is a case of fasting of the larva of Trichodes ammios recorded by Mayet;[[131]] this Insect, in its immature form, destroys Acridium maroccanum; a larva sent from Algeria to M. Mayet refused such food as was offered to it for a period of two and a half years, and then accepted mutton and beef as food; after being fed for about a year and a half thereon, it died. Some Cleridae bear a great resemblance to Insects of other families, and it appears probable that they resemble in one or more points the Insects on which they feed. The species are now very numerous, about 1000 being known, but they are rare in collections; in Britain we have only nine species, and some of them are now scarcely ever met with.
Fig. 131—Larva of Tillus elongatus. (New Forest). A, Head; B, front leg; C, termination of the body, more magnified.
Fam. 57. Lymexylonidae.—Elongate beetles, with soft integuments, front and middle coxae exserted, longitudinal in position; tarsi slender, five-jointed; antennae short, serrate, but rather broad. Although there are only twenty or thirty species of this family, they occur in most parts of the world, and are remarkable on account of their habit of drilling cylindrical holes in hard wood, after the manner of Anobiidae. The larva of Lymexylon navale was formerly very injurious to timber used for constructing ships, but of late years its ravages appear to have been of little importance. The genus Atractocerus consists of a few species of very abnormal Coleoptera, the body being elongate and vermiform, the elytra reduced to small, functionless appendages, while the wings are ample, not folded, but traversed by strong longitudinal nervures, and with only one or two transverse nervures. Owing to the destruction of our forests the two British Lymexylonidae—L. navale and Hylecoetus dermestoides—are now very rarely met with.
Fig. 132—Hydrocyphon deflexicollis. Britain. A, Larva (after Tournier); B, imago.