The Farmer's Apiary
At the present time in Europe, Asia, and America there are probably not far from ten million people who depend in large measure upon the product of the silkworm for their livelihood. Although the product of their industry and that of the insects combined is not nearly as indispensable to man as those which are won from the hair of animals or the fibres of plants—for silk is a luxury rather than a necessity—the value of the work done by these humble creatures is greater than that effected by the largest of our domesticated animals, the elephant. If the philanthropic economist were forced to choose which of these creatures should pass from the earth, he would have to accept the loss of the greater and far nobler animal.
So far as regards their intelligence, the silkworms are much below the level of the bees. Though they dwell in an aggregate way they have scarcely a semblance of social order, and are without the wide range of peculiar instincts which we invariably find among the commonwealth animals. The order of Lepidoptera, in which these creatures belong, though the most beautiful, appears to be from an intellectual point of view the least advanced of our insects. Their instincts are all on a low plane; they have no kind of mutual labor, and however much advance we may make by selection in developing their bodies, there is no reason to expect that we shall affect their intelligences.
The cochineal insect, a species which has the habit of feeding upon the cactus, is used for a dye stuff, for which service the brightly colored body is appropriated. Although the creature is deliberately planted where it is to feed, and thus is in a way submitted to culture, it cannot fairly be said to have been entered in the domesticated circle of man. In a similar way the so-called Spanish fly—which really belongs among the beetles—whose ground-up bodies are used for producing blisters, is merely appropriated to our use without any process of subjugation. The fact remains that, so far as our dealings with the insect world have gone, we have really won but two of the million or more of forms to captivity; and our relations with these have nothing of the humanized nature which marks our intercourse with truly domesticated creatures.
Small as are the lessons which we may read from our experience with the honey-bee and the silkworm, they appear clearly to indicate that, while we may expect to do little with the intelligences of insects, we may fairly reckon on a great field for accomplishment in the way of changes in their bodily constitution. In the case of the bees the facts show us that in particular conditions of climate or other surroundings a certain amount of variation takes place, and by proper selection either of queens or swarms it may be possible considerably to extend the value of these animals. The task is beset with difficulties for the reason that, while in ordinary selective breeding we deal with individuals, we have, as before remarked, in this species to regard the hive or colony as the unit and to make our selection with reference to the qualities of that colony as a whole. Nevertheless, with the constant advances in the skill of our economic selectionists, there is reason to expect that our bees may be progressively improved. On the other hand, there is the chance that the progress of chemical discovery may enable us at any time to manufacture honey in the artificial way and of a quality indistinguishable from that produced by domesticated bees; in which case these captives, at best troublesome, though most interesting, will probably disappear from the human association.
With the silkworms, variations can be more readily brought about; for, as is the case with other animals, the individuals can be paired. The efforts at selection already made show that valuable characters can be thus accumulated, though not with the success which attends the efforts of a like nature made in the case of our domesticated mammals and birds. In common with other animals—indeed, we may say, with all organic life—the silkworms vary perceptibly in different parts of the world to which they may be taken. Thus, when reared in California it is said that this insect develops more strength than it exhibits in Europe; and the eggs which it lays there produce stronger insects, which in turn yield larger cocoons than the individuals born in Italy or France. With such a basis for the selective art as the variations of this insect afford, there seems no reason why it should not afford a good field for the work of the breeder's art.