5o8 



DIPTERA 



harm in Japan by attacking the silkworm, and in the case of this 

 fly the eggs are beheved to be introduced into the victim by 

 being laid on mulberry leaves and swallowed with the food ; 

 several observers agree as to the eggs being laid on the leaves, but 

 the fact that they are swallowed by the silkworm is not so certain. 

 Sasaki has given an extremely interesting account of the develop- 

 ment of this larva. ^ According to him, the young larva, after 

 hatching in the alimentary canal, bores' through it, and enters a 

 nerve-ganglion, feeding there for about a week, after which the 

 necessity for air becoming greater, as usual with larvae, the 

 maggot leaves the nervous system and enters the tracheal system, 

 boring into a tube near a stigmatic orifice of the silkworm, where 

 it forms a chamber for itself by biting portions of the tissues and 

 fastening them together with saliva. In this it completes its 



Fig. 243. — Diagrammatic section of silkworm to show tlie habits of Ugimyia. a^ "Youug 

 larva ; b, egg of Ugimyia in stomach of the silkworm ; c, larva in a uerve-ganglion ; 

 d, larva entering a ganglion ; e, larva embedded in tracheal chamber, as .shoAvu in 

 Fig. 242, B. (After Sasaki. ) 



growth, feeding on the interior of the silkworm with its anterior 

 part, and breathing through the stigmatic orifice of its host ; 

 after this it makes its exit and buries itself deeply in the ground, 

 where it pupates. The work of rupturing the puparium by the 

 use of the ptilinum is fully described by Sasaki, and also the fact 

 that the fly mounts to the surface of the earth by the aid of this same 

 peculiar air-bladder, which is alternately contracted and distended. 

 Five, or more, of the ITgimyia -ma,ggots may be found in one 

 caterpillar, but only one of them reaches maturity, and emerges 

 from the body. The Tachinid flies appear to waste a large pro- 

 portion of their eggs by injudicious oviposition ; but they make 

 up for this by the wide circle of their victims, for a single species 

 has been known to infest Insects of two or three different Orders. 

 The species of Miltogravima — of which there are many in 

 Europe and two in England — live at the expense of Fossorial 



' J. Coll. Jajian, i. 1886, pp. 1-46, plates i.-vi. 



