PREVENTING TIIE ATTACK OF INSECTS, MILDEW, & c . 173 
tedious business, except only on very small trees, which happen to be 
under both the eye and hand. But it is worth consideration whether 
or not it be possible to cover the fruit trees on which the insects lay 
their eggs by some liquid which would offend and drive them from the 
garden and orchard into the fields, where they do but little harm. This 
liquid, whatever it may be, while it offends the mother moths, must 
not spoil or taint the fruit, because it should be applied while the 
insects are in their cocoons, and that is, when the fruit are on the 
trees, say in August or September. But all circumstances considered, 
perhaps the best time to assail this moth, and all other insects infesting 
fruit-trees, is just before and at the time they begin to move in quest 
of food. If, at that time, the trees were thoroughly sprinkled or 
repeatedly washed with some liquid which would either be fatal or 
offensive to the caterpillars, a check would be given on their first irrup¬ 
tion, which, if it did not diminish their numbers, might drive them 
from their prey. 
The aphides are one of the plagues of gardeners. These insects are 
viviparous in warm weather and oviparous in cold. In the first the 
nymphs come forth naked, in the second they are brought forth covered 
with a thin glutinous slough, which serves to attach them to the place 
where they are laid, and to shelter them during winter. In the spring 
they burst their thin covering, and creep to the summit of the shoot 
on which they passed the winter, there congregating to breed and feast 
on the juices of the plant. The aphis is doubly injurious, not only by 
extracting the juices, but by soiling the leaves, and especially the fruit, 
with honey-dew emitted by them. 
Every gardener knows how to banish the green flies ( aphides) after 
they appear, by fumigations of tobacco, either in frames, houses, or in 
the open garden, with the assistance of a fumigating cloth; but pre¬ 
venting their choosing a plant to live and breed on is a desideratum 
among cultivators, and yet to be discovered. Perhaps the means of 
prevention are simple, and near at hand, did we but know them. 
Every decoction offensive to the human palate has very probably been 
tried by one practitioner or another, but, as far as my knowledge goes, 
without success. There are two difficulties in the way: the first is, 
plants, in a state of growth, are ever producing new parts, grateful to 
the insects, however offensive the old parts may be ; and, secondly, 
they are furnished with wings in one stage of their life, by which they 
can transport themselves whither they list. To overcome these diffi¬ 
culties requires a daily, or at least a very frequent application of the 
protective means—a laborious inconvenience quite impracticable. Still 
there is no doubt, but that if a tree could be made offensive to the 
