Fam. 72. Anthicidae.—Head with an abrupt narrow neck; prothorax narrower than the elytra. Middle and hind coxae placed in definite acetabula. Claws simple. These little Insects are numerous in species; they have little resemblance to Pyrochroidae, though the characters of the two families cause us to place them in proximity. There are about 1000 species known; though we have only about 12 in Britain, they are very numerous in the Mediterranean region. The family Pedilidae of Lacordaire and some others is now merged in Anthicidae. Thomson and Champion, on the other hand, separate some very minute Insects to form the family Xylophilidae, on account of certain differences in the form of the abdomen and tarsi. The Xylophilidae live in dead wood; the Anthicidae, on the surface of the earth, after the manner of ground-beetles; very little is, however, known as to their natural history.
Fam. 73. Oedemeridae.—Prothorax not forming sharp edges at the sides, head without a narrow neck. Penultimate tarsal joint broad; claws smooth. These Insects usually have a feeble integument, and bear a certain resemblance to Malacodermidae. Less than 500 species are known, but they are widely distributed, and occur in both temperate and tropical regions. The larvae live in old wood. Nacerdes melanura is common on our coasts, where its larva lives in timber cast up by the sea, or brought down by floods, and it is able to resist immersion by the tide. It is remarkable from the possession of five pairs of dorsal false feet on the anterior segments, and two pairs on the ventral aspect. In Asclera caerulea there are six dorsal and three ventral pairs of these remarkable pseudopods. We have six species of Oedemeridae in Britain, including Asclera as well as Nacerdes.
Fig. 138—Asclera caerulea. A, Larva; B, pupa (after Schiödte); C, imago. Cambridge.
Fam. 74. Mordellidae (incl. Rhipiphoridae).—Head peculiarly formed, vertex lobed or ridged behind, so that in extension it reposes on the front edge of the pronotum; capable of great inflection and then covering the prosternum; hind coxae with laminae forming a sharp edge behind, frequently very large. This family is a very distinct one, though it exhibits great variety. Lacordaire has pointed out that Rhipiphoridae cannot at present be satisfactorily distinguished from Mordellidae. Leconte and Horn separate the two by the fact that the sides of the prothorax form a sharp edge in Mordellidae, but not in Rhipiphoridae. A better character would perhaps be found by a study of the head, but as this would clearly result in a radical change in the composition of the two families it is preferable to treat them at present as only sub-families: if placed on a similar basis to the preceding families, the group would however form, not two, but several families. Besides the unusual shape of the head (Fig. 139, D) the ventral region of the body is remarkably formed, being very convex, and in many Mordellides terminating in a strong spinous process (Fig. 139, C). The elytra are, in several Rhipiphorids, of the groups Myoditini and Rhipidiini, reduced to a very small size, and the wings are not folded. The Mordellidae are remarkable for their activity; in the perfect state they usually frequent flowers, and fly and run with extreme rapidity. Mordellides are amongst the most numerous and abundant of the European Coleoptera, and in Britain the Anaspini swarm on the flowers of bushes and Umbelliferae. The life-histories appear to be singularly varied; but unfortunately they are incompletely known. The larvae of some of the Mordellids have been found in the stems of plants, and derive their nutriment therefrom. This is said by Schwarz to be undoubtedly the case with Mordellistena floridensis. Coquillett has found the larvae of M. pustulata in plant-stems under circumstances that render it highly probable that they were feeding on a Lepidopterous larva contained in the stems; and Osborn found a similar larva that was pretty certainly a Mordellistena, and fed voraciously on Dipterous larvae in the stems of a plant. The little that is known as to the metamorphoses of Mordella and Anaspis shows that they live in old wood, but does not make clear the nature of their food.
Fig. 139—Mordellistena floridensis. America. (After Riley.) A, Larva; B, pupa; C, imago; D, outline of detached head of imago of M. pumila, to show the neck.
Although it has been ascertained that the Rhipiphorides exhibit instances of remarkable metamorphosis, their life-histories are still very imperfectly known. Dr. Chapman has ascertained some particulars as to Metoecus paradoxus, which has long been known to prey in the larval state on the larvae of the common social wasps.[[137]] The eggs are apparently not deposited in the nests of the wasps, but in old wood. The young larva is a triungulin, similar to that of the Cantharidae, we shall subsequently describe. It is not known how it makes its way to the wasps' nests, but it is possible that when a wasp visits some old wood haunted by these larvae, some of them may attach themselves to it and be carried to the wasps' nests. When access is gained to the cells the little Metoecus pierces the skin of one of the wasp-grubs, and entering in it feeds on the interior; after it has increased in size it emerges, changes its skin, and assumes a different form and habits; subsequently, as an external parasite, entirely devouring the wasp-larva, and then becoming a pupa, and finally a perfect Metoecus, in the cell of the wasp. The wasps, though they investigate the cells, do not apparently entertain any objection to the Metoecus, though there may be sometimes as many as twenty or thirty of the destroyers in a single nest. A few hours after the Metoecus has become a winged Insect and has escaped from the cells, it appears however, from the observations of Erné[[138]] on nests of wasps in captivity, that the wasps become hostile to the foreigners, and it is probable that in a state of nature these leave the nest as quickly as possible. Emenadia flabellata, a genus allied to Metoecus, has been discovered by Chobaut to have a similar life-history, except that it attacks a solitary wasp of the genus Odynerus.[[139]] An old record to the effect that a second species of Emenadia, E. bimaculata, lives in the stalks of Eryngium campestre, on the pith, is now thought to be erroneous. Fabre has found the larvae and pupae of another Rhipiphorid in the cells of a bee, Halictus sexcinctus.
The most remarkable of the Rhipiphorids, from the point of view of its habits, is certainly Symbius blattarum, which is now treated as the same as an Insect previously described by Thunberg from specimens found in amber and called Ripidius pectinicornis. This species is parasitic in cockroaches; the male and female are very different, the former being an active winged Insect, while the female is worm-like, differing but little from the larva, and never leaving the body of the cockroach. It is to be regretted that the life-history is not better known. The species has been found on board ship in vessels coming from India; the male has been met with in several European countries, but the female is excessively rare.
Fam. 75. Cantharidae or Meloidae (Blister-beetles, Oil-beetles).--Head with an abrupt neck; elytra and sides of the abdomen without any coadaptation; each claw of the feet with a long appendage closely applied beneath it. This distinct family consists of Heteromera with soft integument, and is remarkable for the fact that many of its members contain a substance that when extracted and applied to the human skin, possesses the power of raising blisters. The life-history is highly remarkable, the most complex forms of hyper-metamorphosis being exhibited. The species now known amount to about 1500; there can be no difficulty in recognising a member of the family by the above characters, except that in a very few cases each claw bears a projecting tooth, instead of an elongate appendage parallel with itself. The penultimate tarsal joint scarcely ever broader than the preceding; the colour and style of markings are extremely varied. There are two very distinct sub-families, Cantharides and Meloides; the former are winged Insects, and are frequently found on flowers or foliage. The Meloides are wingless, and consequently terrestrial; they have a very short metasternum, so that the middle coxae touch the hind; and they also have very peculiar wing-cases, one of the two overlapping the other at the base; in a few Meloids the wing-cases are merely rudiments.