PHILAEMATOMYIA INSIGNIS: EARLY STAGES 359 



select a place for itself. This gregarious habit is worthy of note and 

 has not been observed in the case of any other muscid. 



From the somewhat lethargic habit' of the fly, especially when laying 

 its eggs, and from the fact that it breeds rapidly and, in Madras at least, 

 throughout the year, one would expect to find that it has many natural 

 enemies, which keep down its numbers. The chief of these is a small 

 Hymenopteron (not identified). The habit of this wasp is to settle on 

 the dung and to watch for a fly laying its eggs. Having marked a victim, 

 it crawls up to within an inch or two of it and then makes a short rapid 

 flight, settles on the fly, and after stinging it carries it away, holding it 

 by means of its sting and its hind legs ; as many as five wasps have been 

 seen on a patch of dung preying on insignis. The fly, busily engaged in 

 laying its eggs, usually falls a ready victim, and this is specially the case 

 when it has once inserted its ovipositor, as it often appears to have con- 

 siderable difficulty in withdrawing it in time to escape from the wasp ; 

 when a number are ovipositing together the wasps carry them away in 

 rapid succession. It also attacks the flies while feeding on cattle. Un- 

 fortunately the small size of the wasp and the rapidity with which it car- 

 ries away its victim makes it difficult to locate its nest. 



Several small species of spider also prey on insignis, catching them 

 while laying their eggs. There is also a small Asilid which has the same 

 habit, and can often be seen to swoop down on a fly and carry it off, 

 grasped by its forelegs, to a neighbouring twig, where it sucks out its 

 juices. Lastly, a small tachinid, which is commonly seen resting on a 

 blade of grass close to a piece of dung in which insignis is laying its eggs, 

 behaves in a remarkable and suggestive manner. It sits with its head 

 directed towards the fly, and every now and then darts towards it, in a 

 very direct and business-like manner, and at once returns to its perch. 

 It certainly does not catch or attempt to catch insignis. It is a larvi- 

 parous species, but as to how and where it deposits its larvae it is at 

 present not possible to say. 



The egg of insignis (Plate XLVI, fig. 3) is of the usual muscid type 

 and measures from 2 to 2'2 mm. in length and '4 mm. in breadth. The 

 larvae hatch out in from eight to nine hours, that is, on the evening of 

 the day on which the eggs were laid. When mature they measure 12 

 mm. in length, their greatest breadth being about one-seventh the length. 

 They are of a bright lemon colour and on this account are readily distin- 

 guished from other muscid larvae. They all remain together feeding in 

 the dung up to the evening of the second day, when they migrate in com- 

 pany, passing out from the lower surface ; they bury themselves in the 



