9114. WHEAT, Weevils and.—
The
weevil is a formidable obstacle to the cultivation
of wheat with us. But principles are already
known which must lead to a remedy.
Thus a certain degree of heat, to wit, that of
the common air in summer, is necessary to
hatch the eggs. If subterranean granaries, or
others, therefore, can be contrived below that
temperature, the evil will be cured by cold. A
degree of heat bevond that which hatches the
egg we know will kill it. But in aiming at this
we easily run into that which produced putrefaction.
To produce putrefaction, however,
three agents are requisite, heat, moisture, and
the external air. If the absence of any one of
these be secured, the other two may safely be
admitted. Heat is the one we want. Moisture
then, or external air, must be excluded. The
former has been done by exposing the grain in
kilns to the action of fire, which produces heat,
and extracts moisture at the same time; the
latter, by putting the grain into hogsheads, covering
it with a coating of lime, and heading it
up. In this situation its bulk produced a heat
sufficient to kill the egg; the moisture is suffered
to remain indeed, but the external air is
excluded. A nicer operation yet has been attempted;
that is, to produce an intermediate
temperature of heat between that which kills
the egg, and that which produces putrefaction.
The threshing the grain as soon as it is cut,
and laying it in its chaff in large heaps, has
been found very nearly to hit this temperature,
though not perfectly, nor always. The heap
generates heat sufficient to kill most of the eggs,
whilst the chaff commonly restrains it from
rising into putrefaction. But all these methods
abridge too much the quantity which the farmer
can manage, and enable other countries to undersell
him, which are not infested with this
insect.—
Notes on Virginia. Washington ed. viii, 407.
Ford ed., iii, 271.
(1782)
