188 PHINEAS W. WHITING. 



We have here then four larvae which survived in the prepupal 

 stage for at least four months at room temperature. The experi- 

 ment indicates that in this case dryness has been the cause of 

 the delay. 



From the pupae formed by these larvae, there emerged after 

 the usual time, flies which were of full size and completely 

 expanded. The only difference observed in them from flies 

 having a short prepupal period was the fact that the abdomen 

 was contracted in a dorso-ventral direction. This deficiency, 

 however, was corrected after a few days of feeding and the flies 

 lived for a normal period of time. An extended prepupal stage 

 under warm and dry conditions does not then necessarily produce 

 misshapen flies, which often appeared from pupae formed directly 

 after the feeding period of the larvae and which were permanently 

 deformed, having the abdomen distorted and shrunken laterally 

 as well. 



From this experiment I conclude that hibernation may be 

 undergone in the prepupal period. It is my opinion also that 

 the majority of hibernating flies pass the winter in this condition 

 and that the moistening of the soil in the spring by the melting 

 of snow and the rain induces them to pupate. Many of the flies 

 appearing on warm days in winter probably come from pupae 

 which are apparently not hindered from eclosion except by 

 extreme cold. 



That drying is not the only cause for delayed pupation, I am 

 led to believe from the fact that in many instances larvae have 

 refused to pupate when buried in sand of all degrees of moisture 

 in my various cultures both of L. sericata and of C. cadaverina. 

 While this prolongation of the larval stage was in some cases 

 undoubtedly due to cold, this cause could not be assigned to all 

 cases as they often refused to pupate in summer temperature in 

 moist sand. 



A female of L. sericata, igi2-V, was taken at the Bussey 

 Institution on November 20, 1912. One lot of her larvae com- 

 prising 151 individuals reached the migration stage on December 

 4 and 5. They were distributed in eleven glass jars, but since 

 conditions were the same in some of the jars I have grouped them 

 for convenience into five series which represent the five conditions 



