aris. Though the disaster
happened several years since, he tells us that it will be useless for
him to attempt the raising of silk worms in the town where his
establishment is situated, as the germs of the disease are most
difficult to eradicate.

So direful in France were the ravages of this disease that two of the
most advanced naturalists in France, Quatrefages and Pasteur, were
commissioned by the French government to investigate the disease.
Pasteur found that the infected eggs differed in appearance from the
sound ones, and could thus be sorted out by aid of the microscope and
destroyed. Thus these investigations, carried on year after year, and
seeming to the ignorant to tend to no practical end, resulted in saving
to France her silk culture. During the past year (1871) so successful
has his method proved that a French scientific journal expresses the
hope of the complete reestablishment and prosperity of this great
industry. A single person who obtained in 1871 in his nurseries 30,000
ounces of eggs, hopes the next year to obtain 100,000 ounces, from which
he expects to realize about one million dollars.

[Illustration: The Potato Caterpillar.]

CHAPTER V.

THE CLOTHES MOTH.

For over a fortnight we once enjoyed the company of the caterpillar of a
common clothes moth. It is a little pale, delicate worm (Fig. 57,
magnified), about the size of a darning needle, and rather less than
half an inch in length, with a pale horn-colored head, the ring next the
head being of the same color. It has sixteen feet, the first six of them
well developed and constantly in use to draw the slender body in and out
of its case. Its head is armed with a formidable pair of jaws, with
which, like a scythe, it mows its way through thick and thin.

But the case is the most remarkable feature in the history of this
caterpillar. Hardly has the helpless, tiny worm broken out of the egg,
previously laid in some old garment of fur or wool, or perhaps in the
haircloth of a sofa, when it begins to make a shelter by cutting the
woolly fibres or soft hairs into bits, which it places at each end in
successive layers, and, joining them together by silken threads,
constructs a cylindrical tube (Fig. 58) of thick, warm felt, lined
within with the finest silk the tiny worm can spin. The case is not
perfectly cylindrical, being flattened slightly in the middle, and
contracted a little just before each end, both of which are always kept