OBSERVATIONS ON BLOW FLIES. 



189 



offered. They were kept at room temperature in semidarkness 

 during the day and complete darkness at night. Without excep- 

 tion the flies emerged from the pupa cases in due time. Table I. 

 gives the record of this experiment. 



TABLE I. 



RECORD OF FIRST LOT OF PROGENY FROM L. sericata 



In the first place it is obvious from this table that drying has 

 acted as an inhibitor to pupation while moisture has accelerated 

 it. Thus in Series i we notice considerable delay in pupation 

 produced apparently by the dryness of the environment. In 

 Series 2 on the other hand, the damp sand furnished a very favor- 

 able condition for pupation. In Series 3 are a few pupations at 

 first, and then with the drying out of the loam, pupation ceases. 

 Moistening the medium again produces pupation. The very 

 favorable conditions in Series 4 and 5 may be due to the fact that 

 the sawdust and cloth were kept very moist. Series 5 shows 

 also that it is not necessary that the larvae should have a chance 

 to bury themselves in order to pupate, and this I have observed 

 in large numbers of cases in my cultures where the larvae have 

 readily pupated in wooden boxes as soon as they have left the 

 fish. There is one other thing noticeable here which was not 

 observed in the first experiment and that is that the larvae in 

 the dry sand although slightly slower in pupating than the 

 others have noc entered a condition of indefinite prolongation 



