14 BULLETIN 124, U. S. DEPAETMENT OP AGEICULTUBE. 



ceived at Hanover in strong active condition on June 10. She began to lay on 

 June 11 and continued until June 22. Her 420 adult offspring represent only 

 a part of her caterpillar progeny, for, besides the loss through disease and acci- 

 dent, 15 pupag succumbed to excessive cold and other unfavorable conditions 

 in a refrigerator while undergoing an experiment to determine the effect 

 of cold upon color. Probably 500 eggs were laid. 



The proportion of males to females in Arizona is about 2 to 1, 

 but Gerould, in Xew Hampshire, finds them about equal. In the 

 field at Tempe one will always be impressed with the superabundance 

 of males. This difference in the proportion of the sexes as between 

 Arizona and Xew Hampshire is probably due to the fact that in 

 Arizona the intestinal disease kills a large number of the larvae ; and 

 since males develop a few days sooner than females, it is likely 

 that the majority of the larva? killed w T ould have developed into 

 females, while those escaping the disease become males. In Xew 

 Hampshire Prof. Gerould is often able to rear over 90 per cent from 

 egg to adult in confinement, while at Tempe it is rare that 25 per 

 cent of the eggs are reared. In a blooming alfalfa field the per- 

 centage of males to females is still higher, owing to the fact that fe- 

 males after feeding and mating leave this older alfalfa to seek new 

 growth. In searching out this tender growth for egg deposition it 

 seems as if they knew that if their eggs were laid on the older 

 alfalfa it might be cut before the larvee could mature. One can tell 

 at a glance an ovipositing female. She has a hesitating flight and at 

 intervals will drop down for a moment on an alfalfa leaf and, de- 

 positing an egg, will flutter on, soon repeating the operation and de- 

 positing as many as four or five eggs per minute. 



Among the yellow butterflies in a field one notices many white or 

 albino forms. These are of the same species as the yellow ones 

 and. according to Prof. Gerould, 1 are merely color phases, as he has 

 shown to be the case in Eurymus philodice ( Godart ) . 



FEEDING HABITS OF THE BUTTERFLIES. 



The butterflies of Euryvrms eury theme feed upon nectar from the 

 blossoms of a great many plants. Over a blooming alfalfa field one 

 can often see them by the millions, visiting the blossoms and extract- 

 ing the nectar therefrom. This habit has occasioned many remarks, 

 farmers quite often being under the impression that these butterflies 

 were producing some direct results upon the growth of the alfalfa 

 crop. The bee-keeping farmer usually insists that they are robbing 

 his bees by taking nectar that belongs to them. In Circular 133 of 

 the Bureau of Entomology, published in 1910, the writer ventured 

 the remark, since he had witnessed the tripping of the pollen trigger 



1 Gerould, J. H. The inheritance of polymorphism and sex in Colias philodice. Amer. 

 Nat., v. 45, p. 257-283, May, 1911. 



