Conservation Reader

by Harold W. Fairbanks

This balance among the animals, which comes from one living upon another, is a strange and wonderful thing. No one kind can long overrun its fellows. If one does get a start and increases until it becomes a pest or plague, some enemy is sure sooner or later to spring up to destroy it. We use this method in fighting some of the insect pests which are injuring our trees. Men have searched in various parts of the world from which such pests as the gypsy moth and the San José scale have come to find some of their enemies and bring them to this country to feed on these insects.

When men came upon the earth, they soon began to upset Nature's arrangements, and from that time until now matters of this kind have been growing worse. We have killed large numbers of the beneficial animals and birds that kept the harmful ones in check. We have carried others from the homes given them by Nature, where they were doing little harm, to new homes where they have become terrible plagues.

The killing of large numbers of hawks and owls, all the species of which many people have wrongfully thought to be harmful, has been followed by a great increase in the numbers of rats and mice. We have killed off most of the coyotes, the chief food of which was rabbits and ground squirrels. The two latter animals have now become a serious pest. They do enormous damage to the crops, and we spend thousands of dollars fighting them.

The common rabbit has in most parts of its native country so many enemies which are always on the lookout for a good meal, that it cannot increase enough to do much harm. Years ago a number of rabbits were taken to Australia, where there were none. Here they found a favorable climate and few enemies. They have now increased so that they overrun much of the continent and are a terrible pest which the farmers are unable to control.

Some years ago the gypsy moth and the browntail moth were introduced by accident into the New England states. Finding there a congenial climate and few enemies, they increased rapidly. They soon began to strip the leaves from the beautiful elms which make the streets and parks of this region so attractive. Now these moths have turned their attention to the white pine and are doing an ever-increasing amount of damage; and although they are being fought by every means in our power, we are not certain that we can ever control them.

The codling moth, whose larva is the little apple worm, causes an immense loss in our fruit orchards. The cotton-boll weevil, which destroys so much of the cotton, is, like the codling moth, an insect imported from another country. The San José scale reached California from China and has now spread throughout our country. It has a special fondness for the sap of fruit trees, and, being so small, was not noticed until it had got beyond control. This scale causes more loss than any other of the tree insects.

The Hessian fly, introduced from Europe more than one hundred years ago, causes during certain seasons a very great loss to the wheat crop. The Argentine ant has been brought to us from South America and is proving a most destructive pest. The Norway rat was brought to our country on sailing vessels and causes more loss than most of us realize. The English sparrow has spread over much of the country and is driving many of the native birds from their homes, because of its quarrelsome disposition. It makes itself a nuisance on all our city streets.

The mongoose, in its home in India, is a great rat killer, but does not there increase so as to do much harm. Wherever it has been carried for the purpose of using it as a rat killer, this little four-footed animal has become a terrible scourge. After it destroys the rats it goes after the snakes. Then it attacks the other small animals and birds. Finally it begins upon the chickens, and even the vegetables in the garden are not safe from its voracious appetite.

Men are now watching at every port to see that no more dangerous insects and animals are brought into the country. They are particularly on the watch for the Mediterranean fruit fly and for the mongoose.

When we upset the balance of Nature, we start a whole chain of troubles. What can we do to escape the consequences of our ignorance and carelessness? In the first place we can protect the birds, for they eat enormous quantities of the harmful insects. In the second place we can see that no more of these dangerous pests are allowed to land on our shores. In the third place we shall have to fight, by every means that we can discover, those that are already here.