f-HALCID PARASITES OF Al'STKALIAX SHEEP ?.[AGGOT-FLIES. 115 



During February a sheep's head, spht down the middle. 

 A\as put into a box of dry soil, and infested entirely with 

 Pycnosoma riififacies and P. varipes. After about six days, 

 the head was hfted and about 100 blowfly pupse counted ; 

 as the experiment was intended for other purposes (as described 

 below) the pupse beneath the soil were not counted, but it is 

 significant that after several days thousands of Pycnosomas 

 hatched, the bottom of a box. 2 ft. by H ft., being UteraUy 

 green with them. 



In April results were obtained A\iiich seem to show the 

 effect of heavy rain on puliation. The sheep's heads were 

 ])laced in a box, and became duly infested with Opliyra nigra, 

 Sarcophaga spp., Pycnosoma riififacies, and Lvcilia sericata. 

 Heavy rain fell, the whole contents of the box becoming 

 thoroughly Avet. One portion of the box was more wet than 

 the remainder ; it contained no pupse. No pupse occurred 

 on the surface anywhere in the box, but were all found at a 

 depth of from f to 1 inch beloAv the surface where the soil was 

 least wet. Below this the soil was wetter, and only six pupse 

 Avere discovered in it, but in the relatively drier region above 

 tliis level several hundred were counted. As several thousand 

 pupse had been expected a search was made in the soil 

 surrounding the box, and as a result great accumulations of 

 pupse of all the species were found buried in the soil to the dej)th 

 of one inch under sheltering boards close beside the box. Un- 

 protected soil to a distance of 5 feet from the box was examined 

 and showed the presence of numerous fly-pupse. It would 

 seem, therefore, that during rainy weather the conditions for 

 Xasonia are even more unfavourable, since, though the maggots 

 do not bury themselves so far down in the soil, none pupate 

 on the surface. If these experiments are confirmed under 

 sheep-country conditions, then this chalcid cannot be regarded 

 as even a serious check on the spread of sheep blowfhes. 



These experiments do not take account of another serious 

 deficiency on the part of Xasonia, viz., the alleged inactivity 

 of the parasite at the very time that the fhes are at their worst 

 (Report of Blowfly Committee, Institute of Science and 

 Industry, December, 1920).^ Possibly this is accounted for by 



-As this painphlet is not readily available to workers, we deem it 

 advisable to republish the statements relating to the work of Nasonia 

 at INIr. W. Russell's sheep station, Dalmallj', near Roma, Queensland : — 

 "As occasionally over 80 per cent, of the blowfly pupse are found to be 



