252 



STUDIES IN LIFE-HISTORIES OF AUSTRALIAN DIPTERA 

 BRACHYCERA. 



Part i. Stratiomyhdae. 



No. 2. Further experiments in the rearing of Metopunia ruhrici'.ps. 



By Vera Irwin-Smith. B.Sc, F.L.S., Linneaii Maeleay Fellow of the Soeiety 



in Zoology. 



(Eight Te.xt-figures. ) 



Attempts to rear the larval Metoponia rubriceps from the egg, whieh were 

 made last year and described in the first paper of this series, were continued 

 throughout the Spring and Summer, and have at la.^t met with a considerable 

 measure of success. It has been found possible to breed from flies reared from 

 the larva in . captivity, and the cyele, from larva to the laiva of the next 

 generation, has been obtained. Unfortunately, the bred larvae fill perished 

 at an early stage, so that the cycle is not yet (|uite complete, and the length of 

 time occupied in the larval state has still to be determined. 



The larvae used in the experiments were those collected in May and August 

 of 1020. Early in the following Spring, many began to show signs of the im- 

 mobility which marks the onset of pupation, and, as this occurred, the pupating 

 larvae were put into separate vessels. Common half-pint glass preserving jars 

 were found most suitable for the purpose, filled to a depth of an inch or two with 

 the sandy soil in which the larvae normally live, and planted with a little couch 

 grass, having stems long enough to afford a resting place for the flies as they 

 emerged. The soil was kept slightly damp, and the jars, loosely covered with 

 metal screw tops, were kept on a window ledge where they were exposed to 

 direct sunlight for several hours after sunrise. Each jar contained several 

 pupae, judged by their sizes to ho of the two sexes. 



Under the-se conditions, a good proportion of the pupae completed their 

 development, and imagines appeared over a much longer period than had been 

 observed in the field. The earliest, a male, emerged on 11th October, while 

 others were obtained as late as December. One pupa noticed to be immobile on 

 12th December, was dissected on 10th December, and found to be still in a very 

 early stage of pupation. 



During this Spring, very few of the adult Mies were caught in the field. 

 A long period of drought had evidently proved unfavourable for their develop- 

 ment. The lawn at the Australian Museum, from which the larvae had been 

 obtained, had become very dry, and the earth had caked hard, when it was 

 searched for larvae and pupae on 4th November. Though a good number 



