236 



MR. A. M. ALTSON ON THE LlFE-niSTORY AND 



of Ghalcicls. This experiment, therefore, was a complete failure. 

 The only point of interest was that the two flies placed at a depth 

 of 5 inches reached the surface. 



Experivmid No. 7. — This was also a burrowing test. It was 

 started on 30th January, 1920. The same jar was used as in 

 No. 4. It was filled w^ith 2 inches of damped soil, and on this 

 93 newly formed puparia were placed ; above the puparia 2 inches 

 of damped soil was run in. (The w^riter was now in possession of 

 details of tests 1 and 2.) On the surface of the soil 12 more 

 puparia were scattered, and a piece of liver upon which larvtie 

 had been feeding was also put in. The liver covered five of the 

 surface puparia. The liver was used to reproduce, on a small scale, 

 natural conditions. 20 fertilized females were released in the jar 

 on the same day ; it was covered with bolting silk and smeared 

 with food. The jar was kept under observation. From 31st 

 January to 9th February some of the females could be seen at 

 work on the surface puparia. From 10th Februai-y bo 13th they 

 appeared to be dying. On the latter date C. erytlirocepliala began 

 to emerge, and continued to do so for several days. On 18th 

 February all Hies were dead. On 19th February the contents 

 were examined. The 12 surface puparia were opened, and all 

 found to contain Ohalcids in advanced or early pupal stage, and 

 a few as larvc^e. 72 dead Calliphora were found on the surface. 

 The 93 puparia at a depth of 2 inches below surface were then 

 turned out, and 72 empty puparia were found ; the remainder, 

 21, were still intact, and w^ere opened and examined. No signs 

 of the Ohalcids were found ; the contents of these intact puparia 

 were dead fiies in various stages and atrophied nymphs. 



Experiments Nos. 4 and 6 indicate that female Nasonia, even 

 when confined in a small space with host puparia covered with 

 soil loosely run in, are incapable of burrowing to any extent; and 

 in this connection the following observation of Froggatt (7) is 

 quoted : — " It is generally amongst the pupee of Pycnosoma 

 rufifacies, and to a lesser extent P. varijyes, that this species of 

 Clialcid wasp is found actually at work in the field. This is 

 largely due to the habits of the larvse of these two species, which 

 do not crawl away from a carcase to pupate unless the remains 

 have been much disturbed, but pupate either just under the edge 

 of the remains or else aflix themselves to the bones, wool, or other 

 portions of the carcase, and thus they are more easily found than 

 the other species, all of which generally crawl a considerable 



distance from the carcase, and scatter No definite reason 



can yet be assigned to the apparent distaste of the wasps for the 

 pupse of Opluira nigra and Pycnosoma varipes in the laboratory. 

 In the field the pupae of the latter species are practically always 

 found to be parasitized.*' 



Further, Nasonia does not bear the appearance of a burrowing 

 insect ; its head, viewed dorsally, is widei" than any other part 

 of its body, whereas Melittohia acasta females (specimens of 

 which Mr. Waterston kindh- gave the writer) have a narrow head 



