OBSERVATIONS ON BLOW FLIES. 



The larvae were packed in so closely that their movements could 

 be felt by each other and for this reason they were kept active. 

 Upon being separated into smaller lots they soon pupated with 

 the exception of Series 7. For the delay in this case I have no 

 explanation, and it would appear that there are other unknown 

 disturbing factors. 



A female specimen of Calliphora viridescens (1912-21) was taken 

 in the vicinity of the Bussey Institution, November 20, 1912. 

 Eggs were soon deposited and the larvae attained full growth on 

 or before December u. On that date they were placed in dry 

 sand. No pupae were formed and the larvae were transferred to 

 damp sand on December 18. Another transfer was made after 

 about one week as pupation had not appeared and the larvae 

 were placed in dry sand. On January 7 a count was made and 

 there were found to be 3 pupae, 271 living larvae, undersized and 

 wrinkled, and 13 dead larvae, wrinkled and dry. Of the three 

 pupae, 2 failed to emerge, although flies were formed inside, and 

 the other emerged normally. The larvae were placed in a jar 

 with very damp cloth. Examination was not again made until 

 January 30 when 2 normal flies were found, I cf and I 9 , 20 

 dead larvae, 91 pupae, and 158 living larvae. The cloth was still 

 damp. The larvae were then transferred to a dry glass jar, and 

 by February 15 were all dead and dried up, except that nine 

 misshapen pupae were formed which did not emerge. Of the 

 other 91 pupae which were kept on damp cloth only twelve had 

 emerged by February 15, giving six males and six females. The 

 others were dead. 



The ill luck in getting these larvae to pupate may be explained, 

 I think, by the fact that they were at first crowded and thus 

 disturbed each other. This was the condition up to January 7, 

 a period of at least twenty-seven days, when they were observed 

 to be undersized and wrinkled and some of them had died. 

 Apparently in this case we have a condition very different from 

 that of the first experiment recorded in this paper. It is possible 

 that this may be due to the generic difference of the flies as pro- 

 longation of the larval stage of Lucilice has often been observed 

 to produce the pinkish coloration of the fat bodies, while in all 

 cases the larger species, Calliphorce and Cynomyia, have retained 



