Insects and Parasitic Diseases. 99 



Experiment No. 25. 



Twenty-three pupae of unknoAvn ages, collected on October 2nd, 

 were placed on dry mud, and incubated at a temperature of 22°C. 

 One young fly emerged on the third day, two on the sixth day, two 

 -on the tenth day, two on the thirteenth day, one on the eighteenth 

 day, one on tw,enty-third day, five on twenty-seventh day, one on 

 twenty-eighth day, two on the thirty-first day, and two on the 

 thirty-second day. 



Thus 82.6% of the pupae remained viable, and produced young 

 flies within three to tliirty-two days of their removal from the host. 



Exjyeriment No. 26. 



Fifty pupae of unknown ages, collected on September 7th, were 

 j)laced on dry sand, and incubated at SG^'C. Two young flies 

 emerged on tlie first day. The remaining forty-eight Avere found to 

 l>e dead on October 18th. 



Thus only 4% of the pupae remained viable, for a period of only 

 one day. 



Experiment No. 27. 



Thirty pupae of unknown ages, collected on August 30th, were 

 incubated at 22 ^C. on moist sand. One young fly emerged on the 

 twelfth day, one on the eighteenth day, one on the twenty-third day, 

 and one on the twenty-fifth day. The remaining twenty-six pupae 

 -died. 



Thus 13.3% of the pupae remained viable, and produced young 

 flies within twelve to twenty-five days of tlieir removal from the 

 host. 



E I' peri men t No. 28. 



Forty-six pupae of unknown ages, collected on December 7th, were 

 incubated on moist sand at a temperature of 36.^0. None of these 

 produced young flies. 



Experiment No 29, 



Forty-nine pupae of unknown ages, collected on August 30th, 

 Avere placed on dry sand in Petri dish, which was placed on the 

 lawn within the Institute quadrangle. The dish was exposed to all 

 the prevailing weather conditions, excepting that the surrounding 

 buildings broke the force of the wind, and that a small table which 

 was placed over the dish prevented the rain falling directly upon tlie 

 sand. On clear days the pupae we^e exposed to the direct rays of 



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