62 PSYCHE [June 



WINTERING LARVAE. 



BY F. H. FOSTER, CLAREMONT, N. H. 



Probably every one who has attempted to carr)^ hibernating lepidopterous larvae 

 through the winter has, like the writer, had the baffling experience of complete 

 failure as a general rule, with perhaps an occasional hardy survivor or two as a rare 

 exception. 



One successful experience, however, brings much encouragement, and as I suc- 

 ceeded in wintering a brood of Haploa larvae and bringing forty of them through 

 alive and well this spring, an account of the method followed may be useful to 

 others. 



The larvae were fed indoors until the frost killed their food plants. This was 

 not until November, as the favorite food locally of this genus, Cynoglossi/vi officinale, 

 is quite hardy and survives the early frosts. The breeding cage in which the larvae 

 were reared is five inches wide by twelve long, and eight inches high. The sides 

 and ends are of glass set in a wooden frame. The bottom, which is open, rests on 

 a shallow wooden tray containing a little earth and the top is covered by a removable 

 lid consisting of a wooden frame covered with gauze. When the food supply 

 failed, the cage and larvae were carried into a rather dimly lighted room where the 

 temperature was about 50° FaJir. After a few days the larvae ceased eating 

 entirely and appeared lethargic. 



The cage was then filled quite full of dead leaves nearly dry, and the whole 

 wrapped in several thicknesses of paper to exclude the light. During the winter 

 the cage was kept in a cold attic, and later, as spring approached, in a cool, dry 

 cellar. No careful record of temperature was kept but it probably averaged about 

 40^^. From time to time the cage was opened and the dead leaves lightly sprinkled 

 with water. This was doubtless of importance, as previous experiments indicated 

 that too much and too little moisture are equally destructive to larvae hibernating 

 in confinement. Too much moisture promotes fungus growths, while too little 

 causes the larvae to dry up. The exclusion of light may also be a factor of con- 

 sequence. In the latter part of March some Cynoglossuvi plants which had 

 wintered in a tub in the cellar began to put out new leaves, and about the loth of 

 April the breeding cage was brought into a warm, light room and its wrapping 

 removed. Only a few larvae were in sight, but the stimulus of light and warmth 

 soon brought many others to the top of the cage, and in the course of twenty-four 

 hours some forty appeared and were transferred to new. clean quarters, with fresh 



