Fig. 81.—Cochineal insect, female.
Fig. 82.—Aphis.
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,
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 taken from the roots and the leaves? There is one thing which may reassure us as to the future attacks of
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.