36 The Philippine Journal of Science ww 



puparium. This end of the insect is red-tipped, while the re- 

 mainder is decided golden in color. The color of the whole 

 puparium changes rapidly to burnt sienna. 



The encapsuled puparium is usually from 5 to 9 millimeters 

 in length, depending on the nourishment and care the larva has 

 received. The female has a larger puparium than the male fly, 

 and the female is as a rule 0.5 millimeter longer than, the male 

 from the same lot. 



The male fly takes less time than the female to pass the nymph 

 stage. In more than 40 instances recorded, first emergences 

 were marked by the appearance of males. The male fly usually 

 precedes the female by two days. 



INFLUENCES OF ENVIRONMENT ON THE DEVELOPMENT OF THE NYMPH 



Certain artificial conditions have been found to affect the 

 developing nymph. When kept in water during the whole of 

 this stage, 30 pupse failed to develop ; nor did they develop when 

 removed from the water after seven days and placed in a dry 

 glass after drying on filter paper. The lowering of the tem- 

 perature from that of the room at an average of 29° C. to that 

 of the cold room at 21° C. retarded emergence two to four days, 

 but seemed to increase the percentage of emergences. An ex- 

 posure to the outdoor light and sunshine at a maximum tem- 

 perature of 43° C. killed the developing nymphs, while the light 

 of the room at the same temperature of the darkened cabinet 

 inhibited the development to the extent of two to three days. 



It can be inferred from these experiences that the optimum 

 conditions for pupal development include a dark, cool, moist 

 medium; and these conditions prevail where the puparium oc- 

 curs in nature. 



The length of time spent in the puparium is fairly constant. 

 It is usually never greater than five and one-half days under 

 natural conditions, but when modified by the artificial environ- 

 ment of the laboratory this period may be extended to six or 

 even to ten or twelve days. 



EMERGENCE OF THE FLY 



The pupa gives no indication of movement of any sort, such 

 as occurs in some orthoraphous flies, which might be interpreted 

 as premonitory of emergence. The only sign of activity, to 

 inform the observer of what is occurring within, precedes emer- 

 gence only by a minute or two, and consists of a barely percep- 

 tible rising and falling of the operculum or cap. Immediately 



