123 
Popular Errors with regard to Blight. 
of the eyes, and shrivelling and browning of the leaves of trees and 
hedges, as sultry, thundery weather may sometimes effect. Insects 
being proved by extensive, minute, and accurate experiments, from the 
time of Redi downwards, to be invariably hatched from eggs laid by 
parents similar to themselves, it is utterly impossible they can be ge¬ 
nerated by any state of the air. It is no less impossible, though it has 
been asserted, that the eggs of insects are floated about by blighting 
winds; for insects, with few exceptions, not only glue their eggs upon 
the leaves and other substances where they are deposited, but even 
were the glue dissolved, and the eggs detached, they are far too heavy 
to float in the air, or be carried away by the winds. 
Here then, is the practical error; and a gardener or a farmer who 
believes in the mysterious power of blighting winds to generate insects, 
concludes, that it is as hopeless for him to endeavour to prevent the 
increase of these insects, as to try to chain the winds supposed to 
produce them. Whereas, the fact is, that these insects are all hatched 
from eggs which have been laid the preceding autumn, or early in the 
spring or summer; and if he had been on the look out for these eggs, 
he might probalfly have discovered a considerable portion of them, 
minute though they be, and by destroying them, have thereby saved 
his croj)s from depredation. 
The sudden appearance all at once, of so many insects, which gives 
some plausibility to the popular errors respecting Blight, arises from 
the eggs being all hatched at once, or at least ^vithin a few days. 
In consequence of their minuteness and the peculiar places where 
they are concealed, it is difficult and often impossible to discover the 
eggs of optrides; but it is comparatively easy to find the eggs of leaf 
rolling caterpillars, of which the rose one is poetically celebrated, as 
the “w'orm i’the bud,’' and those which commit such ravages on oaks 
and currant trees, are readily found in little, whitish-grey, round 
patches, about the breadth of a finger nail, or a card-wafer, firmly 
glued to the bark. If these be cut off during the winter, no blight¬ 
ing wind will be able to generate a single insect of that species, any 
more than to create a brood of chickens without eggs. 
If you deem the foregoing remarks on an important subject, of any 
importance, they are much at your sendee. 
I am, &c. 
Lee, Kent, July 7ih, 1831. James Rennie. 
