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was preserved by the agencies which tended to keep down what would 
in time become, and at times did become, pests. Few possibly 
realized, that while insects generally played an important part in the 
propagation of plants, by being the unconscious agents in perfecting 
the fertilization of flowers, they at the same time performed an 
important office in keeping down vegetation by eating the wood, the 
alburnum, or sapwood, the roots, the leaves, flowers, and seeds of 
plants, as well as removing what in the form of decaying and 
putrifying matter might become injurious. It was only when some 
especial ravage was performed that we realized their apparent 
destructiveness, as when the larvz of beetles destroyed thousands of 
trees, locusts devastated a country, caterpillars laid waste the vegetable 
produce, or an affzs ruined our hops or grapes. 
Birds were, as a rule, the agents in keeping down these pests, as 
those knew, only too well, by painful experience, where the birds, 
having been killed off, insects, destructive to their crops, abounded to 
an enormous extent. Other insects, themselves kept under by birds, 
preyed upon their fellow insects. Ichneumon flies deposited their 
eggs within the bodies of larvee, which never became flies or beetles, 
able to propagate their race, while the larvee of some species devoured 
the eggs and caterpillars alike, and so kept them in check. The 
aphides were devoured by the lady-birds, and their larvae; by the 
larvee of lace-wing flies, and those blue-black flies seen flitting about 
flowers, as well as being pierced by ichneumon flies. 
He was partly induced to call attention to this matter by what 
was taking place in France. There some 87,000,000 acres of land 
covered with vineyards, producing on an average 1,100,000,000 gallons 
of wine a year, had, during the last eight years, been plagued by an 
insect pest, the Phyl/oxera vastatrix (closely allied to our well-known 
aphis, or green fly of the hothouse), which, during that time, had 
devastated 4,000,000 acres of French vineyards. Every possible 
device of the chemist had been tried in vain—carbolic acid, creosote, 
coal tar, petroleum, and naptha, with chloride of lime, sulphur, 
sulphide of lime, sulphurous acid, arsenious acid, and bisulphide of 
carbon, one of the most fetid of chemical substances, had each and all 
been used to no purpose. ; 
It was true that some, notably the bisulphide of carbon, killed the 
pest, but it also killed the vines. Some suggested tobacco ; this did 
succeed, but it was found that to strew the ground a foot deep round 
