THE P.ION"0:\IICS OF Al'STKALIAN TABAXIDAE. 43 



fly and eggs practically undisturbed. In this position the chimney and its contents 

 were returned to the water and overhanging plants. Several times during the next 

 hour the fly appeared to be on the point of continuing oviposition, but each time 

 returned to the netting without having extruded any eggs. 



Between 21st and 2vSth April very heavy falls of rain and high winds caused an 

 accumulation of drift (grass, aquatic plants, twigs, cow and horse dung, etc.) to be 

 thrown up on the sloping banks of this and adjacent pools. When examined on 28th 

 April, numerous half-grown to full-grown larvae of T. aprepcs, T. nifinoiaius and 

 T. nigrifarsis were found in the drift and on or under the soil beneath it ; while others 

 were found buried in the grass-covered soil between the outer fringe of the drift and 

 the foot of a stiff loamy bank three or four feet from it (Plate II. fig. 2). The latter 

 were full-grown and were in some cases obviously at rest in the positions in which they 

 intended to pass through the long dry period to follow ; in others they were still 

 burrowing downward. Quite a number of those found in the drift, and especially in 

 that part near the water's edge, were evidently feeding, as shown by the contents 

 of the alimentary tract. Many of these larvae (T. aprepes) were captured and bred 

 out in the laboratory in July and August. 



While turning over the soil and drift on this date several recenth- discarded pupal 

 cases were found and subsequentlv identified as those of T. riifinotahts and T. nigrifarsis. 

 These pupae were almost certainly the product of eggs laid more than a year earlier, 

 since the unusual conditions of the 1919-20 season and the shortness of the possible 

 breeding period (103 da\'s) almost preclude the possibility of their being derived from 

 eggs laid during the current year. No definite evidence has been obtained to determine 

 the maximum period during which the larvae of these insects may remain in a dormant 

 condition, but certain facts suggest that full-grown larvae may, after the usual long 

 resting period and in the face of a drought, postpone their transformation into pupae 

 for six months or more. 



On the same date (28. iv. 1920) and a few yards distant, full-grown larvae of T. 

 aprepes were found making their way up a slope from the water's edge, through 

 short wet grass and litter towards a bank (similar to that shown in Plate II, fig. 2) 

 and about eight feet from the water's edge. Some were actually travelling when 

 observed, others were sheltering in the grass or under debris. 



These banks were examined four months later (30th August), when several T. 

 aprepes (three pupae and five larvae) were found, and on the same afternoon an adult 

 female was captiired in the vicinity. The period (winter) intervening between these 

 dates, 28th April-30th August, had been unusually mild and moist, doubtless favouring 

 early development and rendering the emergence of the adults possible after even 

 a light shower of rain. During the preceding year, owing to drought conditions, 

 emergence of adult flies from this soil would have been a physical impossibilit}^ 

 throughout the whole period April 1919 to January 1920. 



Oviposition. In discussing breeding-places brief reference has been made to two 

 flies which were observed in the act of ovipositing on 2nd and 16th April. As the 

 process differed in several respects from that recorded for Indian and American 

 species, it may be of interest to refer to it more fully here. At about 4.30 p.m. on 

 2nd April, whilst sitting by the water's edge (Localitj^ 1), a Hy was seen to ahght 

 on the underside of a twig about four feet above the surface of the pool (Plate I) 

 and about three feet from my head. The twig lay at an angle of about 45° to the 

 water, and the fly settled on it head uppermost. After lightly touching the surface 

 of the twig many times with the tip of the abdomen, the first egg was extruded whilst 

 only the extreme apex of the abdomen was flexed. Immediately the apex of the egg 

 touched the twig it appeared to stick, and as it left the body it was forced out of the 

 vertical position to an angle of about 20° ; the apex of the abdomen was again applied 

 to the twig at the point of attachment and to one side of the egg just laid and a second 



