The Insect World: Being a Popular Account of the Orders of Insects; Together with a Description of the Habits and Economy of Some of the Most Interesting SpeciesFiguier, Louis
Science
The Insect World: Being a Popular Account of the Orders of Insects; Together with a Description of the Habits and Economy of Some of the Most Interesting Species
Figuier, Louis
Insects
To give an idea of the losses which may be occasioned by the pyralis,
in a period of ten years (1828-1837), twenty-three communes comprised
in the two departments of the Saône-et-Loire and of the Rhône lost
75,000 hectolitres of wine a year, which may be valued at 1,500,000
francs. If we were to calculate the supply of articles of all sorts
which this great number of casks of wine would have necessitated, the
imposts on their transport, the duty, the taxes levied on their sale,
the carriage by land and water, which would have brought receipts into
the treasury, and lastly the diminution of taxes which had to be
granted for seven years to the vine proprietors in the department of
the Saône-et-Loire, and in 1837 in the department of the Rhône, and
which amounted to a total of more than 100,000 francs, we shall find
that the ravages of the pyralis caused in these two departments an
annual loss of 3,408,000 francs, and as the visitation lasted ten
years, we get the enormous sum total of 34,000,000 destroyed by the
ravages of one species of insect. The moth of the pyralis (Fig. 287)
shows itself from the 10th to the 20th of June. It is yellowish, more
or less shot with gold. When at rest, its wings are folded back one
over the other like a roof. Its flight is of short duration; it
contents itself with going from one vine stock to another.
[Illustration: Fig. 287.--The Vine Pyralis.]
[Illustration: Fig. 288.--Caterpillar of the Vine Pyralis.]
It is at sunset mostly that you see the moths of the pyralis
fluttering about. They remain quiet during the day, particularly when
the sun is at its hottest. They live on an average for ten days. The
females lay their eggs--which are at first green, then yellowish, then
brown--on the lower surface of the leaves.
[Illustration: Fig. 289.--Chrysalis of the Vine Pyralis.]
The caterpillar of the pyralis (Fig. 288) is called, in vulgar
parlance, according to the different places in which it occurs, vine
worm, summer worm, vintage worm, shell. In the south of France it is
called, in the patois of Languedoc, _babota_. Almost immediately after
they leave the eggs, the little caterpillars hide themselves in the
fissures of the vine stocks or the props which support them. They spin
a small cocoon of a greyish silk, in which they remain curled up till
the month of May. From the moment the leaves begin to develop they
throw out threads here and there, entangling all the young shoots of
the vine, which gives a desolate appearance to the vineyards. The
leaves of the vine are their favourite food, but they attack the seeds
of the grape also. As they increase in size every day, the damage they
do goes on increasing, and has not reached the maximum of intensity
till the moment when the caterpillars are about to change into
chrysalides. They are then three-quarters of an inch long and of a
yellowish green colour.
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