Series VI. Rhynchophora.
Head more or less prolonged in front to form a snout or beak, called rostrum. Tarsi four-jointed, usually at least the third joint broad and densely pubescent beneath.
This enormous series includes about 25,000 species, and as may well be imagined shows a great variety of structure amongst its forms. The vast majority may, however, be readily recognised by the two characters mentioned above. There are some cases in which the beak is indistinct, and others in which the tarsi are five-jointed (Dryophthorus), and even slender (Platypides). In these cases a close examination shows that the gular region on the middle of the back of the under surface of the head cannot be detected, and that the back of the prosternum is very strongly consolidated by the side-pieces of the thorax meeting together and being very firmly joined behind the coxae. The beak is in the great majority perfectly distinct, though it varies so extremely in form that it can only be briefly described by saying that it is a prolongation of the head in front of the eyes, or that the antennae are inserted on its sides near to, or far from, the tip. It has been ascertained in many cases that the rostrum is used by the female to assist in placing the eggs in suitable places, a hole being bored with it; in some cases it is also used to push the egg far into the hole in which it has previously been placed by the ovipositor; but there are many forms in which it is fairly certain that it is not so used. What purpose it serves in the male is totally unknown. In many members of the series, the rostrum differs in form in the two sexes, and in most, if not in all, these cases it is clear that the distinctions tend in the direction of making the beak of the female more efficient for the mechanical purpose we have mentioned.
Fig. 147.—Eugnoristus monachus ♀. Madagascar. A, The imago; B, front of pronotum, head, and rostrum.
It was proposed by Leconte and Horn to separate this series from all the other Coleoptera as a primary division, and they looked on it as of lower or more imperfect structure. Packard has very properly protested against this interpretation; and there seems to be no reason whatever for considering the Rhynchophora as "lower" than other beetles; indeed we should be inclined to place such forms as Calandrides amongst the most perfect of Insects; their external structure (as shown by Eugnoristus monachus, Fig. 147) being truly admirable.
Only four families of Rhynchophora can be at present accepted as satisfactory; one of these—Curculionidae—includes an enormous majority of the whole series. Though it is probable that it will ultimately be divided into several families, the attempts to that end that have already been made are not satisfactory.
Fam. 80. Anthribidae.—Palpi usually not covered, but distinct and flexible. Antennae often long, not elbowed, the first joint not very long. Third joint of tarsus small, usually much concealed by being embraced by the second joint. Pygidium exposed; propygidium deeply grooved in the middle. This family includes 800 or more species, which are mostly tropical; it is very sparsely represented in the faunas of Europe and North America. It is quite distinct from Curculionidae with which it was formerly associated. It contains many graceful Insects having a certain resemblance with Longicorns on account of the large development of the antennae. The habits and metamorphoses are but little known. It seems probable that many species find their nutriment in old wood or boleti The larvae of some genera (Cratoparis and Araeocerus) have legs, but in others the legs are wanting, and the larvae are said to completely resemble those of Curculionidae. In the larva of our tiny British species, Choragus sheppardi, the legs are replaced by three pairs of thoracic, sac-like pseudopods. This Insect makes burrows in dead branches of hawthorn. The larvae of the genus Brachytarsus have been ascertained to prey on Coccidae.
Fig. 148—Platyrhinus latirostris, Anthribidae. Britain. A, the perfect Insect; B, tarsus and tip of tibia.