HABITB OF TWO PARASITES OF BLOW-FLIES. 235 



Table V. — Depth of Soil penetrated by pamsitized larvae. 



* 2 dead. 



■!■ 2 dead. 



writer was in posse.ssion of the information gained in experi- 

 ments jSTos. 3 and 4. 



Earperiment No. 5. — A cylindrical glass jar was used. It was 

 filled with 5 inches of damped soil ; on this was placed a piece of 

 liver with some larvae feeding upon it. They were mostly full 

 grown. This experiment was started on 20th December, 1919. 

 On 22nd December it appeaxed that the larv* had ceased feeding 

 and had gone into the soil to' pupate. The liver was therefore 

 removed, and under it two puparia were found ; no others were 

 visible. The liver was replaced, 18 fertilized females of Nasonia 

 hrevlcornis were then released in the jar, which was at once 

 covered with bolting silk, and this smeared with food. On 

 1st January, 1920, adult G. enjthrocephala were emerging; no 

 Ohalcids could be seen, so no further supplies of food were given. 

 The flies were left to die, so that nothing should be disturbed. 

 Adults continued to emerge up to 5th January ; a few days later 

 they were all dead. On 10th January, as no living adults could 

 be seen, neither flies nor parasites, the two puparia on the 

 surface were removed, and the contents of the jar emptied and 

 sorted. No attempt was made to gauge the depth to which the 

 larvae had crawled. The jar was found to contain 47 empty 

 puparia and an equal number of dead flies. 14 intact pujjaria 

 were found ; these were opened, and yielded four puparia con- 

 ta.iuing Chalcid larva3 ; the remainder consisted of dead fully- 

 formed flies or atrophied fly-nymphs with no sign of Chalcids. 

 The two puparia from the surface were filled with Chalcid larva;. 

 Of the Chalcid females, only 15 were collected ; the other three 

 were not searched for a second time in the soil. 



Uxperiineni No. 6. — This was another burrowing test, in which 

 20 puparia, were placed at various depths ranging from two at 

 5 inches to seven on the surface, and were situated near the glass 

 side so as to be visible to the ol)server. The soil used was very dry 

 and lumpy, with a certain amount of fine dust due to the crumpling 

 of the lumps. Four females and one male were released in the 

 jar. Mating was observed. The experiment started on 1st 

 January 1920; and on 20th February, when the contents were 

 emptied and the intact puparia opened — there were only four of 

 these, flies had emerged from the rest,- -none bore Rxiy signs 



