these beings as riders on both the vegetable and animal kingdoms to restrain them with a bridle. What the

gardener does to plants, the aphis has often done before in order to arrest a too vigorous and rapid growth. The cochineal insect (Coccus cacti) Figs. 80 and 81,

Fig. 80.-Cochineal insect, male (Coccus cacti), natural size and magnified.

originally from Mexico, lives on the cactus nopal as a true parasite, and furnishes a precious colouring matter, carmine. This insect has been introduced into

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Fig. 81.-Cochineal insect, female.

Fig. 82.-Aphis.

the Antilles, Spain, the Canary Isles, Algeria, and Java.

Lake is produced by a species of the same genus, originally a native of India (Coccus lacca).

Aphides (Fig. 82) feed on the sap of plants; they multiply rapidly without the male insect. Rose-trees, and more especially their buds, are attacked by a species of a green colour, of which we give a representation (Fig. 83).

An aphis, the Phylloxera vastatrix, has, a short time since, invaded the vineyards, and small as it is, it is dreaded as a plague which scatters ruin in its path. According to recent observations this insect has a double series of generations which precede each other: the mother type and the tubercular type. But this polymorphism seems to be more apparent than real,

taken from the roots and the leaves? There is one thing which may reassure us as to the future attacks of

although there is a considerable difference in their manner of life and of procuring nourishment. Is this difference the result of the different kinds of food

the phylloxera, that Mons. Planchon has just discovered in America the cat of the phylloxera, one of the acaridæ, its mortal enemy; and it is only necessary to multiply these in order to destroy this terrible pest of the vineyards. We thus see that we have only to imitate this so-called blind Nature, in order that we may arrest a misfortune against which man is unable to protect himself by his own powers.

We will here repeat what we wrote respecting aphides some years ago. Who does not know these small green bodies, of the size of a pin's head, coming like a cloud upon the buds and leaves of the rose bushes, which shrivel and wither immediately? There are green ones on certain plants, and black ones on others, but whatever be their colour, they are living pearls which form garlands round the stalk. The world considers them as vermin, and they scarcely dare to touch them with the point of their fingers. To the naturalist they are a little world of wonders. Let us examine with a magnifying lens these walking grains of sand; each grain will reveal to us a charming insect, whose head is adorned with two little antennæ, and has globular projecting eyes glistening with the richest colours; behind these are two reservoirs of liquid sugar, elegantly mounted on a polished stalk, and always full; long and slender limbs support the globular body.

Much has been written about these small sugar manufactories, so well known by ants that they have procured for the aphis the name of ant-cow. Among the curious phenomena presented by these grains of animated dust, that which most interests us relates

to the secret of their astonishing, we may say, their prodigious fecundity.

Nature requires millions of aphides in a few hours, to arrest the exuberance of vegetation, and as if she distrusted the assistance of the male insect, she dispenses with it, and the female brings into the world a daughter already prepared to produce a grand-daughter. Generations succeed each other with such rapidity, that if the daughter at her birth were to meet with any obstacle in her passage, the grand-daughter might come into the world before her mother; a single egg can produce in the course of one season milliards of individuals. Each plant has its own aphis, and in many localities the ravages of the Aphis laniger are but too well known, though it was unknown in Europe a quarter of a century ago.

The Gyrodactylus elegans, of which we have spoken above, contains embryos similarly enclosed, and if these facts had been known at an early period, the celebrated theory of the enclosure of germs, so warmly advocated by Bonnet, would have preserved still longer its intrepid defenders.

With but few exceptions, all the Hemiptera are parasites of the vegetable kingdom. There are only very few which attack animals. There is one 'species, the name of which may be readily guessed (Acanthia lectularia), which pursues us relentlessly everywhere, for it will wait for months and years, always equally greedy of our blood. It surprises us during the night, and does not wait till its digestion is complete before it attacks us again. Happily for us, another hemipterous insect, the masked reduvius (Redurius personatus) penetrates like