In the fourth tribe, Aprosterni, WESTW., there are insects equally curious and destruc tive as in the preceding. The true Aprosterni are distinguished chiefly by their soft flexible elytra, by an entire absence of any process from the sternal surface of the prothorax, and by the dilatation of the margins of the pro thorax, which anteriorly covers the base of the head. Some exceptions exist to these charac ters in the Bostricide and their congeners, which ought perhaps to be removed to another tribe. In the Lampyrida (glow-worms), (figs. 335 and 336), there is an example of a circum stance not uncommon among insects, the pos session of wings by the male sex and their entire absence in the female. The Ptinide or death-watches, and other Xylophagous insects of this tribe, although small, are exceedingly destructive to furniture and the wood of houses; and the Bostricide and Scolytidee to living trees. It is an insect of this family, Scolytus de structor, that of late years has occasioned in calculable mischief to the elms in St. James's Park and Kensington Gardens, and in the park at Brussels. So lately as the summer of 1836 nearly eighty fine elms were cut down at the latter place and its neighbourhood, in con sequence of decay occasioned by this pest.* Another species S. pygmeus, which attacks the oak, has destroyed many thousands of young trees in the Bois de Vincennes.f Ano ther genus, Tomicus typographus, was so de structive in the IIartz Forest in Germany du ring a series of years from the beginning of the last century to 1783, that the number of trees destroyed by it in that forest alone was calcu lated at a million and a half.: In the third section, Pseudo-tetramera, WEszw., the species have one false and four dis tinct tarsal joints to their legs, with pulvilli or hairy cushion on their under surface, and the ante-penultimate joint is bilobed and broader than the others. The section is divided into two tribes.
In the first tribe, Rhynchophora, (fig. 337), the head is elongated in the form of a snout or rostrum, at the extremity of wbich is the mouth, and at the sides are inserted the antenna which are usually geniculated and club-shaped. The larva of these insects are generally apodal, and many species are exceedingly injurious to the blossoms of the apple, pear, and other fruit-trees. Both the larva and perfect indi vidual of one minute species, well known as the " weevil," Calandra granaria, closely al lied to fig. 337, occasion immense losses in the storehouses of the factor by attacking and destroying his corn. The parent insect not only feeds upon the corn itself, but deposits a single egg in every grain, and the larva when hatched devours the whole excepting the husk.
The second tribe, Longicornes, (fig. 338), are known chiefly by the great length of the antenna', which usually exceeds that of the whole body. Their mandibles are strong and pointed ; the body elongated and depressed ; and the prothorax, which is often tuberculated or spined, is narrower than the abdomen. Their larva: are short, thick, and apodal, and are furnished with strong mandibles, and live beneath the bark or in the wood of trees.
The third tribe, Phytophoga, KT RIIY, is also composed of pseudo-tetramerous insects, with pulvilli on their tarsi, and is divided into two sub-tribes. In the first, Eupoda, the body is of an elongated oval form, the head is sunk deeply into a narrow prothorax, and the thighs of the posterior legs are greatly enlarged. In the second sub-tribe, Cyclica, the body is of a rounded or oblong oval (fig. 339), the base of the prothorax is narrower than that of the elytra, and the antenna, which are of moderate length, are inserted widely apart from each form, are never terminated by a pectinated club. It includes many genera of dissimilar habits, the darkling-beetles, Blapsida-, the meal-bee tles, Tenebrionide, and the Cantharidet, the oil-beetles and blister-flies.
In the sixth section, Brachclytra, (fig. 341), other. It is an insect of this tribe, Hallica nemorum, that often occasions so much injury to the agriculturist by destroying his crops of turnips immediately after the young plant ap pears above ground. The perfect beetle, scarcely larger than a millet-seed, deposits its eggs upon the under surface of the first leaves, and the larva when hatched penetrates into the substance of the parenchymatous tissue, be tween the cuticle of the upper and under sur face of the leaf, where it lives until it is ready to undergo its transformations in the ground.* In some years the plants are attacked by such prodigious numbers of these insects that many thousand of acres are destroyed in a few days. The loss sustained by the devastations of this insect in Devonshire in 1786, is said to have been not less than £100,000 t In the fourth section, Pseudo-trimera, WEST. the insects have only three distinct joints in their tarsi, although a fourth one, exceedingly minute, and which like the additional one in the Tetramera was first noticed by Messrs. Kirby and Spence,/ exists at the articulation of the last joint, as in the insects of the third section. The Pseudo-trimera are distinguished by their tarsi, by their oval or hemispheric shape, and by the antennae ending in a three-jointed club. The larva are hexapodous and active; those of the common lady-cow, Coccinella, feed upon aphides, and other genera upon fungi.
In the fifth section, Ileteromera, there are five joints in the first and second pairs of legs, but only four in the third, (fig. 340). The palpi, four in number, are large and projecting, and the antennw, usually filiform or monili the body is elongated, and terminated by two exsertile papilla', the elytra short, quadrate, and often covering only the meso- and meta thorax ; the true or posterior wings, folded be neath the elytra ; head broad and flattened, mandibles large, hooked, and pointed, antennae often enlarged towards their extremities, and the tarsi of all the legs five-jointed. The larva are active and voracious, and undergo a complete metamorphosis.