354 MEDICAL ENTOMOLOGY 



eggs, in cow dung; each egg is 1*5 mm. long and has a delicate dark 

 spine about two-thirds its length. The larva passes through only two 

 moults, the second being missed ; it therefore matures rapidly, and 

 according to Portschinski this compensates for the small number of eggs 

 laid by the imago. In the Crimea in the early spring, and occasionally 

 in the summer, it lays eggs in the usual way, but towards the end 

 of spring and throughout the summer larvae were almost exclusively 

 deposited, one at a time in cow dung ; on examining these larvae 

 Portschinski found that they were already in the third stage of develop- 

 ment. The puparium is white and closely resembles that of Musca 

 convexifrons. 



Portschinski does not appear to have examined the internal genital 

 organs of Musca corvina ovipara, so that it is not known whether they 

 differ according to the season. 



Musca corvina, Fabr. (vivipara, Portschinski.) This species differs 

 from the variety ovipara in the following respects : The male vivipara 

 is considerably larger (7'5 to 8'5 mm.) than that of ovipara ; the first 

 abdominal segment is not entirely dark and there is a well-marked silvery 

 band on the second and third segments, on each side of the median dark 

 stripe ; in addition there is a pollinose lateral band. The female vivipara 

 is also larger (7 to 8 mm.) than the female ovipara, but the markings are 

 very similar. 



This species colsely resembles Musca bezzii, and Professor Bez/d 

 informs us that its puparium is dark brown ; as noted above that of 

 ovipara is white. It seems very probable, as Professor Bezzi suggests, 

 that Portschinski has confused two closely allied muscids, one oviparous 

 and the other larviparous. Both species are common in Europe and 

 parts of North Africa.* 



As all the above species of Musca lay their eggs in cow dung they 

 can be bred in large numbers without difficulty. Musca pattoni always 



oviposits in dung where it is collected in heaps, and it 

 Breeding technique L 



is only necessary to watch a female laying her eggs, 

 and later to transfer the dung to a tray, adding to it a larger quantity. 

 The puparia will be found in the dung in about a week. Musca gibsoni 

 and Musca convexifrons oviposit in isolated patches of cow dung, 

 and in order to collect their larvae it is best to put some fresh cow dung 

 in a tin tray and place it near a cow on which the flies are feeding. 



* The above descriptions of Musca corvina ovipara and Musca corvi-na viviparu 

 are compiled after an examination of a long series of named specimens of both sexes sent to 

 one of the writers by Professor Bezzi and Baron Surcouf. 



