[Inclosure in No.
138.—Translation.]
Locusts in Russia.
[From the Journal de St.
Petersburg, September 4–16,
1879.]
Mr. Portchinsky, secretary of the Russian Society of Entomology, having
been sent last summer to the southern provinces of the Empire to
ascertain what places grain locusts (anis opolia
austriaca) prefer to lay their eggs in, has made numerous
researches in the province of Pultava and has come, the Gazette of
Agriculture tells us, to the following conclusions:
The grain-locust generally deposits its eggs in wheat-fields, and as soon
as they are hatched the attacks of the insects on the grain commence.
There are generally from 20 to 50 locusts per square archine (an archine
is 27 inches) of wheat. Rye and barley fields contain comparatively much
fewer larvae (from 2 to 5) a square archine, but if these fields are
near wheat-fields the larvae are then just as numerous.
The fields which have been sown with wheat the preceding autumn are the
receptacles of an immense quantity of larvae, which it is impossible to
destroy before they have become chrysalids.
The state of the fields whence the owners have driven the locusts is very
different. The pursued insects fly in masses to the neighboring fields,
and the wheat-field where they have fought these insects does not retain
more than 3 to 16 larvae a square archine; on the other hand all the
fields of flax, buckwheat, oats, &c., which are not generally
attacked by the locusts, become infested and contain from 16 to 26
larvae an archine.
It follows that the use of ropes or machines to drive away the locusts is
very dangerous, because instead of laying eggs in wheat-fields, where
they may be destroyed in the spring while in the state of chrysalids,
they settle upon the surrounding fields, no matter what they are sown
with.
Experiments made on the spot by Mr. Portchinsky prove that the larvae
turned up by the plow re-enter the earth quickly, but if they can be
kept exposed ten minutes to the sun they infallibly perish under its
heat. He concludes that in the spring, when the larvae (become
chrysalids) are in a state of complete immobility, plowing the fields
will be of great use, because the chrysalids exposed to the action of
the sun will certainly perish.
As to fighting the locusts by destroying its eggs, Mr. Portchinsky
considers this to be impossible, inasmuch as the period during which the
eggs remain in the ground, before they become larvae, is precisely that
during which the grain is standing.
Mr. Portchinsky is convinced that this year the locusts have left only an
insignificant number of larvae, which permits us to hope that the crops
of 1881 will run no serious risk in this respect.
As to next year, according to the researches he has made in three
townships, the fecundity of the locusts has been very great.
He concludes that as the wheat-fields of last year contained 20 to 50
larvae a square archine, we get, counting only an average of 30 larvae a
square archine, a total of 648,000 locusts to the “deeiatine,” (.37 of
an acre). In the village of Kroutoyar, where the wheat-fields cover 200
deciatines, each archine contained at least 50 larvae. It follows that
these 200 deciatines will contain next year more than 2,000,000 of
locusts, and that consequently, if the spring of 1880 is favorable to
the increase of this insect, we must unfortunately expect great ravages
from it.
