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SCIENCE 



[N. S. Vol. XXXIII. No. 843 



surface of the hind wings. Since aqueous ink 

 will not flow readily enough, the pigment used 

 should be dissolved in 50 per cent, alcohol, and 

 applied with light strokes of a stub pen. 

 Anilin dyes are convenient, as they are readily 

 soluble and can be obtained in almost any 

 color, but for general use any carbon ink that 

 is not precipitated by mixing with 50 per cent, 

 alcohol is preferable, because more permanent. 

 The live butterfly, held firmly with smooth- 

 tipped entomologists' forceps clasped across 

 the fore and hind wings close to the body, 

 objects very little to light strokes of the pen, 

 and the alcoholic ink dries quickly. 



For the designation of a family from a 

 single mating, that is, the progeny of one 

 female, I use a small letter, reserving the cor- 

 responding large letter for the original wild 

 female. The individuals of each family as 

 they pupate, or, if more convenient, as they 

 emerge from the chrysalis, are marked with 

 arabic numerals written at the right of the 

 family letter, like an exponent. In butterflies 

 of course these numbers may run up to over 

 100. In one family of Colias philodice that I 

 raised during the season of 1910 there were 123 

 brothers and sisters. Suppose this family were 

 the offspring of the wild female, " A," and 

 were called " a." The last to pupate (or to 

 emerge) would be " a^'l" To facilitate the 

 handling and recording of large families, it is 

 sometimes well to raise the successive batches 

 of eggs laid by a single female separately, 

 designating each successive lot with a numeral 

 written as a coeificient, so that 2?i'° would 

 mean the tenth butterfly to pupate (or to 

 emerge) in the second lot of eggs laid by the 

 mother of family " n." The name and pedigree 

 of this female, and that of her mate, would be 

 recorded, of course, at the head of the sheets 

 on which the dates of pupation and eclosion of 

 their offspring are set down. 



No elaborate outdoor quarters are needed 

 for keeping and mating live butterflies. The 

 air of the laboratory needs only to be fresh and 

 fairly moist, as that of the ground-floor rooms 

 of large buildings of brick or stone is likely 

 to be in summer. The parched air of a steam- 

 heated room, or of one upon an upper floor and 



flooded with direct sunlight, is more fatal to 

 butterflies than complete absence of food in a 

 moist atmosphere. Bottomless cages 15 inches 

 in length and breadth and 10 inches high, con- 

 sisting of a simple frame of pine strips covered 

 inwardly with cotton mosquito netting, are of 

 ample size for Colias philodice^ serving as a 

 vivarium for the pupae, as an enclosure for 

 mating, and as a cage for the female during 

 egg-laying, if the food plant is small enough 

 to be covered by a frame of this size. The 

 use of wire screening is not to be recommended 

 for adult butterflies, as it soon wears out and 

 disfigures the wings that beat upon it. A 

 frame of this sort covered with cheese cloth, 

 or better with the material known by milliners 

 as frame covering, makes an excellent breeding 

 cage for even the youngest larvae. 



The imago that has just crawled up from its 

 chrysalis rests until the blood flows from the 

 abdomen into the tiny pupal wings. In Colias 

 philodice this requires about five minutes, but 

 the wings after reaching full size remain limp 

 for about a half hour ; and marking should be 

 deferred until they harden. Then the males 

 of each family may be placed together in one 

 cage, the females in another. On the day fol- 

 lowing eclosion they will be ready to feed, and 

 bouquets moistened with a solution of honey 

 and water, or brovm sugar, should be placed in 

 the cages. 



It is surprising to a beginner to see how 

 readily live butterflies may be handled in the 

 absence of direct sunlight or intense diffuse 

 light. Even out of doors, after sunset or in 

 the early morning, they may be allowed to 

 creep upon the finger wet with sweetened 

 water, and feed. They are attracted by a 

 warm moist hand, as by a flower, and on hold- 

 ing them by the costal margin of the wings 

 with one hand, and allowing them barely to 

 touch with the feet a moist finger or palm of 

 the other, they may be stimulated to extend 

 the tongue and begin feeding. Once feeding 

 has begun, they may be moved to a generous 

 drop of honey and water and allowed to drink 

 their fill. In dull, cold weather butterflies 

 neither feed nor lay, and it is necessary in 

 midsummer, when metabolism is rapid, that 



