It is the same with birds. As soon as severe cold begins to prevail in the north and east, they come in troops to the open fields and the sheltered slope of the hills of our district. But it is scarcely worth while to stop to tell of the skill and perseverance of these destroyer of larvæ. We may mention, the woodpecker, however, as a skillful searcher for insects that lie hidden in places where the sun has melted the snow. The carnivorous Coleoptera and the Forficulæ are likewise generally in motion during mild winters. Doubtless these last-named do not make very large inroads in the ranks of larvæ and chrysalids every day; yet, having no other food, they destroy a goodly number of them. But I believe that the devastations made in the army of insects by all these enemies united do not equal those made by certain crustaceans—the wood lice.
During mild winters these pests multiply, eat, and prosper out of bounds, and to such a point that, in a climate like ours, they become a true scourge that prevails everywhere, out of doors and within. Once in a place, they begin to look for larvæ and chrysalids, which they devour. The severe cold seems to have destroyed a certain number of them, since they are now not so numerous by far; and it has at least certainly put a stop to their devastations at an epoch when the larvæ are more particularly exposed to the attacks of their enemies. It is to this cause, as well as to the preceding, that I am led to attribute the extraordinary multiplication of so many species during the three last summers, which were separated by severe winters. Last winter was mild, and there is therefore no reason to expect that there will be another multiplication; but I hope that the harm done by such a season will be slight. It is the progressive multiplication of the destroyers, joined to the correlative disappearance of the victims caused by a series of temperate seasons, that is to be feared.
In support of the proposition that I maintain, I may mention still another fact. While this district (Pembroke, Wales) is relatively poor in species whose larvæ feed and hibernate in the open air a few species of Noctuellæ, whose larvæ live buried in the earth, are always abundant. The country is relatively rich in spices of Tortrix, which develop and hibernate in the stalks or roots of plants. It is also worthy of remark that very few of our species seem to be incapable of enduring a severe winter.—C.G. Barret, in Science et Nature.
SILK WORM EGGS.
Prof. C.V. Riley, entomologist, announces that the Department of Agriculture, Washington, will purchase during the coming summer such quantities of silk worm eggs as may be deemed necessary for the distribution that it is proposed to make for the season of 1886. So far as found practicable, the eggs will be purchased of American producers. There are certain precautions, however, that must be taken to insure purchase. Eggs of improved races only (preferably of the French or Italian Yellow Races) will be bought, and the producer should send one or two samples of pierced cocoons with the eggs. In addition to this the producer must conform to certain rules to be hereafter explained, so that an examination may be made that will serve to show the degree of purity of the eggs. No silk culturist should use his crop for the production of eggs unless the worms have shown, until they began the spinning of their cocoons, every sign of perfect, robust health. Any indication of the disease called flacherie, from which the worms so often die after the fourth moult and turn black from putrefaction, or of any other disease from which silk worms suffer, should be considered as ample reason for not using the cocoons for the purpose in question. They should, on the other hand, be sold for the filature. If the worms have all the indications of health until the spinning period, then the cocoons may be used for the production of eggs. The following brief instructions will prove of service to those who which to secure sound eggs:
For each ounce of eggs to be produced, about three-quarters of a pound of fresh cocoons from the finest and firmest in the lot should be chosen. These should be strung in sets upon a thread, care being taken not to pierce the chrysalis, and the strings hung in a cool, darkened room. The moths generally emerge from the cocoons early in the morning, and will be seen crawling about over these, the males being noticeable by their smaller abdomens, more robust antennæ, and by their greater activity. The moths should be placed, regardless of sex, on a table, where they will soon find their mates and couple. As soon as formed, the couples should be removed to another table, that they may not be disturbed by the flutterings of the single moths.
There should be prepared for each ounce of eggs to be produced, about one hundred small bags of fine muslin, made in the following manner: Cut the cloth in pieces 3×6 inches. Then fold one end over so as to leave a single edge of about three-quarters of an inch, as shown in the accompanying cut. This should be sewn up into a bag with the upper end open, and then turned inside out, so that the seams will cause the sides to bulge. Thus completed they are called "cells." The cells should be strung on a cord stretched across the room.