XIV INTRODUCTION. 



insect enemies that could have accounted for all their troubles, had they understood 

 them. 



Modern agriculture teaches the advantages of a rotation of crops, and it would 

 be as unwise to plant an orchard where one of the same kind of fruit had stood 

 before, as it would be to plant corn or sow wheat for a succession of seasons in 

 the same field, unless it should be some alluvial spot of inexhaustible fertility. Most 

 practical farmers know well that every soil can be exhausted by almost any crop 

 under this improvident management. That has been the fate of large sections of 

 this country. But proper rotation and more systematic manuring are changing all this. 

 The soil is now made tb produce paying crops, and can just as well be made to pro- 

 duce paying crops of fruit as anything else, if the trees and the fruits they bear are 

 protected from the insect enemies. No farm will produce paying crops of wheat 

 where the Hessian fly or wheat midge has taken possession. No prudent farmer 

 will gather his crops year after year into barns infested with the weevil. We might 

 as well suppose that the owner of a valuable flogk of sheep that had been killed off 

 by dogs, would expose another flock to a similar danger. 



Fifty years ago the land in large sections of the State of New Jersey was consi- 

 dered " worn out." Whole counties were in a condition similar to that of the 

 exhausted tobacco lands of Maryland and Virginia, but at that very time the State 

 was famous for its crops of fruit. According to the census of 1860, the farming land 

 of the State of New Jersey was worth about twenty dollars an acre more than the 

 farming land of any other State in the Union. This is partly owing to its proximity 

 to the markets of New York and Philadelphia, but chiefly to the great improvement 

 in the productiveness of the soil by the use of marl and lime, two most valuable fertili- 

 zers found in great abundance. But the fruit crops of New Jersey have diminished 

 in as great a ratio as the value of the lands has increased. This cannot be owing to 

 the exhaustion of the soiL What, then, is the cause ? In large sections of the State 

 the Tent caterpillar is so numerous that the Apple trees are stripped of their leaves 

 every year. Twenty and thirty nests are often seen on a single tree, and large 

 orchards scarcely cast more shade than in winter. The leaves of trees are vital 

 organs, the functions of which are similar to those of the lungs in animals. The 

 Canker worms, Palmer worms, and several other species of caterpillars that feed upon 

 the leaves of our fruit trees, are injurious just in proportion as they destroy these 

 leaves. The owners of such orchards seldom disturb these caterpillars, and yet they 

 complain of the premature decay of their trees, and tell you that raising Apples does 

 not pay. 



The Apple and Quince trees have no greater enemy than the Apple-tree Borer. 

 One whose attention has never been called to the signs of the depredations of this 

 insect will not suspect its existence till too late ; while others who have investigated 

 it carefully, will know its presence in an orchard by the appearance of the trees, even 

 while passing them rapidly in a train of cars. This enemy is often brought in the 

 young trees from the nursery. It is three years in coming to maturity, and increases 



