510 STUDIES IX LIFE-IIISTORIES OF AUSTRALIAN DIPTERA BRACHYCERA, I., 



For the next two or three weeks Hies continued to emerge in the large glass 

 jar, containing grass sods, iu which these larvae were confined. They made 

 tlieir appearance successively on the 19th, 23rd, and 30th April, anil 3rd and 

 4th May. With the exception of two females on the 23rd, these were all males. 

 By this time most of the remaining larvae of the larger size had been chloro- 

 formed and dissected. Some twenty of them were found in various stages of 

 pupation within the larval skin; the rest still retained the unaltered larval struc- 

 ture. 



On the 30th April, a second imago, a male, emerged from among the larvae 

 collected in the previous November. These two are the only ones of this collec- 

 tion which have emerged to date (September, 1920). Six of the larvae are still 

 alive, but none of them show any signs of pupating as yet. 



After an interval of one month, on the 13th May, the ^Museum lawn was 

 again examined. Imagines were now very scarce, only one male and two females 

 being observed. There was a corresponding scarcity of mature larvae in the 

 soil, but numerous empty larval skins were found on, or close to, the surface. 

 In the deeper levels, among the terminal rootlets of the grass, smaller larvae 

 were still plentiful. Over forty were collected in a few spadefuls of earth, the 

 smallest of them being barely 2 mm. long, while others ranged up to 6 and 7 mm. 

 A few larger larvae were found closer to the surface. Of these, three were found 

 to contain female pupae, two of them being dead, and already beginning to decay. 

 From a fourth, a dead and dried, but fully-formed male imago was taken. 



It seemed evident that the smaller larvae belonged to one or several younger 

 generations which were burrowing down to pass the winter at deeper levels, as 

 the mature larvae migi-ated to the surface to pupate. But it was necessary to 

 follow them up, later on in the winter, in order to find out just what had Ijecome 

 of them. Accordingly, on the 3rd August, another examination of the lawn was 

 made. On this occasion the soil was very damp after five or six weeks' con- 

 tinual rain, and only a small area of gi-ound, about the size of the surface of the 

 spade, was dug up. No larvae were found close to the surface, but eighteen, 

 varying in size from 5 to 11 mm., were found among the terminal rootlets, at a 

 depth of three or four inches, four larvae, from 5 to 8.5 nuu.. a little lower 

 down, and three from 7 to 8.5 mm. at a slightly greater depth. 



It will thus be seen that larvae of very varying sizes occur at aU periods of 

 the year, and that except when they are about to pupate, most of the larvae 

 are found always at a depth of two or three inches below the surface. 



Living lar\ae of all sizes, from 4 to 9 mm., and of all collections, from No- 

 vember onwards, are still being kept under observation, though a good many 

 have died or been lost, owing to the predations of rats and mice, which infest 

 the laboratories of the Macleay Museum, and appear to have developed a taste 

 for fly larvae. On several occasions glass pots left overnight uncovered, or with 

 loosely-fitting covers, have been fomid in the mcjrning witli the soil ovcrfnnnMl, 

 and all the larvae gone. 



lAfe-cjicle. 



Fargeau and Scivillc, as early as 1825, (|Uoting Macquart's description of 

 Paehygaster ater, made the statement that the larvae require more than a year 

 for their complete development. And West wood (1S40) says that the larva of 

 Clitellaria cpliippium found by Van Roser, although more tluan half-grown when 

 found, was two years in arriving at the perfect state. Later writers appear to 

 have paid very little attention to this question of the period occupied in the life- 



