a, new and sufficient quantity of froth, which it takes care to add to its first stock. "'^ It is in the froth that the larvai change into pupae, and they do not leave their habitation to undergo their final metamorphosis. They have then, says De Geer, the art of causing the froth inside to evaporate and dry up, in such a manner as to form a space inside the mass of froth, in which their bodies are entirely free. The exterior froth forms a roof closed in on all sides, under which the insect lies quite dry. In this vaulted cell the pupa disengages itself little by little from its skin, which first splits up along the head, and then on the thorax. This opening is sufficiently large to enable it to come out of its envelope. It is in the month of September that these insects are particularly abundant, and then the trees and plants are covered with them. Sometimes the froth drips off, like a sort of small rain, from branches which are covered with it. Towards the autumn the females are pregnant. They are then so heavy that that they can hardly jump or fly. The males, on the contrary, make prodigious bounds; they throw themselves forward to a distance of more than two yards. They are very difficult to catch, and still more difficult to find again when one has once let them escape. And so Swammerdam calls these insects Sauterelles-Puces (Flea-Grasshoppers), because they jump like fleas. All that we have said relates to the Aphrophora spitniarin, or Froghopper (Fig. 85), an insect common all over Europe, and which

Fig. 8s.-The Froghopper GeoffVoy calls the Cigak bedeaude. {Aphrophora spnmaria). " It is of a brOWU COlour," SayS GcoftrOV, " often rather greenish. Its head, its thorax, and its elytra, are finely dotted; on these last one sees two white

oblong spots. The lower part of the insect is light brown, "f

We will mention, as it belongs to the group with which we are now occupied, a noxious insect, lassus dei^astans, which since 1844 seems to have taken up its quarters in the commune of Saint Paul, in the department of the Basses-Alpes. It sucks the leaves and stalks of cereals, causing them to wither, and may be found even in winter on young corn, but principally in the spring. According to M. Guerin-Meneville, its head is of an ochrey yellow, with the apex.

" Memoires pour servir a THistoire des Insectes," tome iii. t " Histoire abregee des Insectes, dans laqaelle ces animaux sont ranges dans un ordre methodique." In 4to. Tome L, p. 416. An VII. de la Republique.

Fig. 8s.-The Froghopper {Aphrophora spnmari

HEMIPTERA,

marked with black spots; the forehead yellow, elongated, striped with black, as are the legs. The elytra are straw-coloured and spotted with brown. The wings are transparent, and slightly blackened at

Fig. 86. 1. Hypsauchenia balista. 3, Centrotus cornutus. S- Bocydium globulare. 2. Membracis foliata. 4; Umbonia Spinosa. 6. Cyphonia furcata;

the extremities. This remarkable insect, which is not more than the twelfth of an inch in length, jumps and flies with great ease.

A small brownish insect, whose strange appearance struck Geoffroy, the historian of the insects of the environs of Paris, may

Il6 THE INSECT WORLD.

be seen springing over the fern stalks and thistles, in the damp parts of most of the woods of Europe.

Geoffroy calls this insect "le Petit Diable." '' Le Petit Diabie," he writes, "is of a dark blackish-brown. Its head is flat, projecting but slightly, and, as it were, bent downwards. Its thorax, which is rather broad, has two sharp horns, which terminate in pretty long points on the sides. In the middle of the thorax is a crest or comb, which, prolonged into a sort of sinuous and crooked horn, terminates in a very sharp point, reaching to within one quarter of the extremity of the wing-cases. These — viz., the wing-cases — are dark, with brown veins; and the wings, shorter than their cases, are rather transparent. The insect jumps very well, and is not readily caught.*

The Petit Diabie of Geoffroy is the Centrotiis coniutus of modern naturalists. This curious little insect belongs to a strange and remarkable group, whose thorax takes the most extraordinary and most varied forms, as may be seen in Fig. 86, which represents somewhat magnified, many of these insects. Nearly all inhabit Guiana, the Brazils, and Florida. We will now proceed to examine one of the most interesting groups of insects — that of the Plant-lice. These insects have for a long time attracted the attention of naturalists. They are so abundant that all our readers have seen them, and there are few plants in our fields or gardens which do not nourish some species. How often does one hesitate in gathering a rose or a bit of honeysuckle, for fear of touching the unattractive guest of those charming flowers!

During the whole of the summer one sees on the branches, on the leaves, but principally on the young shoots of the rose-tree, large companies of green plant-lice, which subsist on the sap of the tree. Some are provided with wings (Figs. 87, 88), others are wingless (Figs. 89, 90). The last-named are the largest, and are a line and a half long. They are entirely green, except two parts, of which we will speak immediately. The body is oval; the head is small, and furnished with two brown eyes. The skin is smooth, and tightly drawn over the body. The antennas, which are very long and slender, almost equal to the body in length. The six legs are long and slim, and the short feet terminate in two hooks. On the upper part of the body are two small cylindrical horns, surmounted by a small knob. The antennae and these horns are black.

The winged individuals are of the same size as these, but are of a

" Histoire abregee des Insectes, dans laquelle ces animaux sont ranges dans unordre methodique." In 410. Tome i., p. 434. An VII. d" U Republique,

HEMIPTERA.

dark green colour, mixed with black. The wings are transparent, Ij and the upper ones are as long again as the body. The young shoots 1 of the elder-tree, all round their circumference for the length of i\ from a foot to a foot and a half, are often covered with black plant-i lice, or with those of a greenish-black colour. They are crowded one j against the other, and sometimes there are two layers of them.

Fig. 87, 88. — Winged Aphides, or Plant-lice (magnified).

If observed without moving the plant about, they appear to be tranquil and inactive. They are, however, then absorbing from the plant the nourishment it should have; piercing with the point of their trunks the epidermis of the leaves or stalks, and drawing from them a nourishing liquid. But this occupation is confined to those which are on the plant itself Those which, on account of the enormous agglomeration of

, 90. — Wingless Aphides, or Plant-lice (magnified).

these insects, walk, not on the branch, but on other plant-lice, and cannot therefore suck the sap of the plant, are employed entirely in preserving and multiplying their species.

Reaumur often saw the latter, easily recognised by their great size, giving birth to little plant-lice, which are quite alive when they leave their mother. The young ones set off and mount or descend till they reach one end of the crowd, and there each takes up its position, hke a cardboard capuchin {capucin de carte), in such a manner

that the head is just behind the plant-louse which precedes it. There they bury their trunks in the vegetable tissue, and set to work to imbibe the sap. Small as is the trunk of the plant-louse, yet when there are thousands of those little beings fixed to the stalk or the leaves of a plant, it is evident that it must suffer. And so the plant-louse is, in truth, one of the most terrible enemies of our agricultural and horticultural productions, and the exact list of the ravages which it occasions would be indeed interminable. We will confine ourselves to

a few examples. For some years the lime-tree aphis has seriously attacked the lime-trees of the public promenades of Paris. The peach-tree plant-louse causes the blight of the leaves of that tree. It is to these prolific little parasites that are due, in a great number of cases, the contortions of leaves and of the young shoots of trees of all sorts.

These insatiable depredators cause sometimes a still more remarkable alteration. On the leaves of elms are often seen bladders round and rosy, like little apples. On opening these bladders one finds that they are inhabited by a species of aphis. On the black poplar galls of different kinds grow, some from the leaf stalks, and others from the young stems. They are rounded, oblong, horned, and twisted into a spiral. Other galls show themselves on the leaf itself. They are all inhabited by plant-lice, differing from those of which we have given a description above, in the extremity of their abdomen not presenting the two remarkable horns to which we shall have later to call the attention of the reader. The body is generally covered with a long and thick down.

Of this genus, the species, alas! so unfortunately celebrated is the Apple-tree Aphis (Myzoxy/e mali), which attacks that tree. This insect is of a dark russet brown, with the upper part of the abdomen covered with very long white down. Its presence was announced for the first time in England in 1789, and in France, in the department of the Cotes du Nord, in 181 2. In 1818 it was found in Paris, in the garden of the Ecole de Pharmacie. It had become common in 1822 in the departments of the Seine, the Somme, and the Aisne. Iii 1827 its presence in Belgium was announced.

The apple-tree aphis, according to M. Blot, can only exist on that tree. Carried away and placed on any other, it very soon perishes. It does not attack the blossom, the fruit, or the leaves, but fixes itself on the lower part of the trunk, whence it propagates itself downwards as far as the roots, underneath the graftings, &:c. It also likes to lodge in cracks of the trunk and large branches. But it always

HEMIPTERA. Iiq

looks out for a southern, and avoids a northern aspect. It is not active, walks very little, and its dissemination from one place to another can only be explained by the facility with which so small an insect can be transported by the wind, its lightness being still more increased by the down which covers it.

The Myzoxyk 7?iali renders the wood knotty, dry, hard, brittle, and brings on rapidly all the symptoms which characterise old age and decay in attacked trees. M. Blot recommends the following means for preserving the apple-tree from this insect: Employ for the seed-beds the pips of bitter apples only; give to the nursery and to the plants only as much shelter as is absolutely necessary; avoid those sites which are too low and too damp; encourage the circulation of air, and the desiccation of the soil; surround the foot of each apple-tree with a mixture of soot or of tobacco and fine sand.

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