NOTES ON THE MYIASIS-PRODUCING DIPTERA. 241 



and in the subcutaneous tissues ; Dermatohia hominis, Hypoderma bovis and 

 Cordylohia anthropophai^a are good examples. Chrysomyia hezziana must also be 

 placed in this group, for its larvae are true dermal parasites of man. I have had 

 examples of its larvae sent me from such small skin punctures as are made in boring 

 the lobes of the ears for ear-rings, and in small cuts on the skin. The only difference 

 between a case of myiasis caused by the larvae of Chrysomyia bezziana and that of 

 Cordvlobia anthropophaga is that, in the former, it is a massed infection, while in 

 that of the latter it is only one larva which causes the myiasis. In the former the 

 tissues rapidly break down and suppurate, while in the latter they do not. Both 

 are specific myiasis-producing Diptera. 



(3). Larvae infesting the intestinal and urogenital tracts. — Tlie larvae of these 

 species feed, to a lesser or greater extent, on the food contained in these organs, 

 especially in the gastro-intestinal tract. In this group Bishopp includes those species 

 whose larvae accidentally find their way into the intestinal tract, such as the larvae of 

 Fannia canicularis and those of many species of Sarcophaga, and those Oestridae 

 whose larvae live in the intestinal tract of animals. I should like to point out that 

 two categories are here involved ; in the one case, the larvae only accidentally pass 

 into the gastro-intestinal tract, the species concerned normally breeding outside the 

 human body, whereas in the case of the Oestridae mentioned, the larvae can only 

 live in special parts of the alimentary tract. Species with such chstinct habits cannot 

 be placed in the same group. 



(4). Forms infesting the head passages. — In this group Bishopp includes those 

 true parasites of man and animals, the larvae of which live in the nose and its acces- 

 sory sinuses, the throat, etc. Here again, this group would have to include Chrysom- 

 yia bezziana, for its larvae also live in the nose and accessory sinuses, and are true 

 human and animal parasites. In the one case the tissue destruction is not great, 

 ■^fhereas in the other it is often extensive. 



(5). Bloodsucking forms. — In this group Bishopp includes those species whose 

 larvae are blood-suckers. Blood-sucking can, however, hardly be considered a form 

 of myiasis, for then we would have to include in this group all the blood-sucking 

 Diptera. 



I have said enough to show that the various methods of grouping the myiasis- 

 producing Diptera according to the tissues or organs attacked, or the methods of 

 attack, are not satisfactory. I am of opinion that the subject is best considered 

 from the standpoint of the habits of the flies themselves, which then naturally fall 

 into three groups as follows : — 



(1). Specific myiasis-producing Diptera. 



(2). Semi-specific myiasis-producing Diptera. 



(3). Accidental myiasis-producing Diptera. 



I will now give a few notes on the adults, hosts, geographical distribution, etc., 

 of the species belonging to the various groups, reserving the notes on all the larvae 

 imtil their identification is dealt with. 



Specific Myiasis-producing Diptera. 



In this group I include all those Diptera whose larvae are found onh^ in living 

 tissues, the flies selecting a number of tissues or organs, or one particular organ, 

 depending on the species, in which or near which to lay their eggs or deposit their 

 larvae. The following species are included in this group : — Chrysomyia bezziana, 

 Cvrdylobia anthropophaga, C. rodhaini. Wohlfahrtia magnifica, and all the Oestridae. 



Chrysomyia bezziana, Villeneuve.- — As I have mentioned above, this species 

 is the specific myiasis-producing Calliphorine of India, Burma, Assam, Ceylon and 

 Africa. Its larvae are commonly found in the nose and accessory sinuses, the mouth. 



