LIFE HISTORY AND HABITS. 31 



phytic. An attempt was made to rear some of the pupa3 in the plas- 

 ter-of-Paris cages, but the cages seemed to be too damp, and all the 

 pupte died. These appeared like those killed in the flooded cages, 

 and the same bacterium and fungus infested them. 



VITALITY OV THE PUPA. 



The pupal stage is the most unprotected state in the life cycle of 

 this insect, and is the one wherein the insect is most liable to mechan- 

 ical injury. A small percentage of the pupae dug up out of doors 

 were injured when their pupal cells were broken open, and conse- 

 quently died. On the whole, however, the pupa is not nearly so 

 susceptible to injuiy as is the popular belief. Such pupse as were 

 unearthed in the field were kept under artificial conditions and 

 handled quite roughly and often, yet most of them produced adults. 

 The two pupse which were photographed for this bulletin (see PL V) 

 were handled several times with forceps, were exposed on a glass plate 

 to light and temperature for hours, and on one occasion were dropped 

 from the table to a chair, a distance of about 10 inches. In spite of 

 this treatment both produced normal adults, and when last observed, 

 October 14, 1912, were alive. There were several similar cases in 

 which the results were the same as in the example cited. The pupse 

 are quite helpless and are unable to make new pupal cells in case the 

 old ones are destroyed. For this reason, probably, a large per- 

 centage of those disturbed in the field die from exposure. The pupae 

 are sensitive to light, heat, and contact, and when disturbed move 

 their abdomens in such a way that the tip describes a circle. As 

 the pupa becomes older it becomes more deeply colored and more 

 sensitive and active. 



CHANGES IN COLOR OF THE PUPA. 



The first signs of coloration of the pupa are the eyes, and these 

 appear as dusky bluish spots. The abdomen and thorax then be- 

 come slightly yellow and the mouthparts and wing covers very 

 faintly dusky. The tip of the abdomen remains whitish. About a 

 week l)efore emergence the entire pupa becomes darker, and just a 

 few days before emergence the wing covers and mouthparts are 

 fliute dusky and the eyes assume a dusky color, the mouthparts, 

 eyes, and wing covers remaining a little the darkest and being quite 

 conspicuous. 



LENGTH OF THE PUPAL STAGE. 



The length of the pupal stage under laboratory conditions varied 

 from 25 to 36 days, with most of the adults emerging in about 26 

 to 32 days. These were kept as nearly as possible under conditions 

 which would compare favorably with field conditions. This gives, 

 roughly, a period of a month for the pupal state. 



