office of a leader, by which the growth of the season is preserved, at the expense of the comeliness of the tree. The subsequent yearly accretions of wood will be in a direction tending to bring the trunk into symmetrical form, but perfect symmetry will never be reached. The formation of wood may proceed quite as rapidly after as before the injury, but the value of the timber will be lessened, especially if, as sometimes happens, similar injuries follow in succeeding years.

These insects are more plentiful and destructive on warm, sandy soils than on low and colder ones. In wet swamps they are seldom found, and, consequently, trees growing in such places are more symmetrical and taller than those of the same diameter growing upon uplands. In selecting a location for a pine forest, low land should be preferred, for this, and probably for other reasons.

ALDEN S. BRADFORD, Supervisor.

25

INSECT-EATING BIRDS.

MIDDLESEX NORTH.

Prize Essay by FRANK H. PALMER, Boxford.

[The following Essay was presented at the fair of the Middlesex North Agricultural Society and received the first prize of fifty dollars offered by the Massachusetts Society for the Preven. tion of Cruelty to Animals.]

The practical utility of our native birds as agents for the destruction of noxious insects can hardly be overestimated.

By studying the

habits of birds

and insects we

may easily dis

cover the impor

tant part which

each plays in the

economy of na

ture, and history

itself proves that

any material interference with their relations to each other is sure to be followed by disastrous results. Hence the subject becomes of deepest importance not alone to the agriculturist but to

every one who has either a business or patriotic interest in our country. Nature, if left to

Fig. 1.-Sparrow-hawk. Tinnunculus Sparverius. (Raptores.) herself, estab

lishes a wholesome balance amongst her creatures; that is,

she produces no more of one species than shall be kept in check by another. If there is an insect which feeds upon a certain plant, there is also a bird

which destroys the insect and an animal which devours the bird; and so on up the scale, each curbing the undue ncrease of the next inferior creature. It is when man interferes with the working of this law that results are sure to follow disastrous alike to his own food, health and happiness and that of the creatures around him. It is because he has destroyed their natural enemies that insects have become a pest, and they will cease to trouble him only in proportion as he shall restore the balance of which nature shows the necessity. It is not that insects are to be destroyed or condemned as a class. Nothing is created except for the fulfilment of some good end, and the value of insects is not inferior to that of any other class of animal life; none are without their legitimate uses, and it is only when they are stimulated to excessive

fabricate the beautiful coral which is so useful and valuable to man. Of similar origin, too, is silk, which, in its manufacture, furnishes profitable employment to multitudes of men,

women and children, and brings in large revenues to the country. Insects we must thank for honey,-the sweetest of sweets. The air we breathe and the water we drink are kept pure and wholesome, by the agency of myriads of little creatures which draw sustenance from the impurities of the elements. It is not, then, that insects are to be exterminated, even if it were possible, but only kept in check.

RELATIVE FERTILITY OF BIRDS AND INSECTS.

The majority of our native birds have but

one brood of

Fig. 5.-Upper fig. Wood-Pewee. Contopus virens. Lower fig. Kingbird. T. carolinensis. (Insessores.)

young in the

course of the year, a few have two or three. In the case of the smaller insect-eating birds the number of eggs to a brood is on an average not more than five. Some of the larger birds, as the various Gallinæ, lay from five or six to twenty eggs to a brood. On the other hand the reproductive energy of insects is truly

marvellous. It

is said that a

single pair of grain-weevils have produced six thousand young between April and August. The common varieties of aphides

or plant-lice which are found on almost all kinds of plants are produced in spring from eggs laid the season before, and through the summer only females are developed. At the last of the season

males and fe

males both appear, and eggs are laid for the brood which hatches early in the spring. Reaumer says that one individual in one season may become the progen

itor of six thousand millions.

Fig. 6.-Chuck-wills Widow.

The silk-worm moth produces about five hundred eggs; the great goat-moth about one thousand; the tiger-moth one thousand six hundred; the female wasp at least thirty thousand. There is a species of white ants, one of which deposits not less than sixty eggs a minute, giving three thou sand six hundred in an hour. How then shall this enormous mass of insects be kept in check? What shall prevent them from overrunning the country, destroying the crops and devastating the land?

FOOD OF BIRDS.

Various causes operate to check the undue increase of insects, and the chief of these is the appetite and instinct, which a wise Providence has given to birds. If the number of eggs produced by insects is wonderful, the number destroyed by a single bird is no less so. Audubon says a woodcock will eat its own weight of insects in a single night. Dr. Bradley says that a pair of sparrows will de

Fig. 7.-Woodpeckers.

stroy three thousand three hundred and sixty caterpillars in a