TENACITY OF LIFE IN INSECTS.

However useful insects may be in the general economy of nature, it is
but too true that farmers and gardeners often find them a pest, and
with each returning summer the pages of agricultural journals abound
with remedies, offensive and defensive, against the obnoxious
invaders. In such cases, it becomes desirable to know what remedial
means are the most efficacious, and we are glad to find that the
question has been taken up by persons competent to discuss it. Among
these, Dr J. Davy has given the results of his inquiry in a paper, 'On
the Effects of certain Agents on Insects,' which has just been
published in the Transactions of the Entomological Society, and is
well worth reproduction in a condensed form. The experiments were
begun in the winter of 1850, the season, as will be remembered, being
so mild that insects were readily met with. Their objects were
threefold--to test the effects of temperature, of gases, and of
vapours. In the former, recourse was had to extremes of heat and cold.
A bee placed in a temperature of 32° became at first more active, but
the next morning was found torpid, as if dead; a register-thermometer
shewing that 25° had been the lowest temperature during the night.
Transferred to a temperature of 52°, the bee revived in half an hour,
and on the following day exhibited the same results under the same
conditions. A fly which, on December 8, was lively on the wing, in a
temperature of 52° indoors, was disinclined to move at 40°; and still
more so, stirring only when touched, at 33°, but did not become
torpid, as in the case of the bee, even at 23°, signs of life being
distinctly visible. Several trials made with different species of
flies all gave the same result--a remarkable power of sustaining life.