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NOTES ON THE MYIASIS-PRODUCING DIPTERA OF MAN AND 



ANIMALS. 



By Major W. S. Patton, M.B., F.E.S., LM.S. (rtcl). 



Lecturer on Entomology and Parasitology, Edinburgh University. 



(Plates V & VL) 



Myiasis has been defined by Austen as follows : — " There remains yet a third 

 category of flies, chiefly belonging to the great Family Muscidae, the larval stage of 

 which is sometimes actually passed in the living human body, the presence of the 

 larvae in the various organs and tissues, and the disorders or destruction of tissue 

 caused thereby, being comprehensively known as Myiasis." It wfll be noted that this 

 definition only refers to the larval stages of flies, but as the eggs, and in one case at 

 least, pupae and adults, may be found in the human body, and as myiasis is a comtnon 

 condition in many animals, the definition may now be amplified as follows : — The 

 condition or conditions, resulting from the invasion of the tissues and organs of man 

 and other animals by all the stages of the Diptera. 



In the latest edition of Castellani and Chalmer's "Manual of Tropical Medicine" 

 (1919) species of flies belonging to no less than ten families have been incriminated 

 as causing myiasis in man ; there is very Httle doubt, however, that the identification 

 of some of the species is more than doubtful. These lists do not even include the 

 most important myiasis-producing Calliphorine of Africa, Chrysomyia bezziana, Vill., 

 so that the information given on this subject must be considered very incomplete. 

 This is chiefly due to the fact that it is difficult to breed the flies from larvae recovered 

 from cases of myiasis, in order to be sure of the identity of the species, and unfortu- 

 nately in most cases identification of species by larvae alone is not yet possible. 

 Although specimens of larvae are doubtless plentiful in museums and private collections, 

 their respective adults, accurately identified, are, on the other hand, scarce. 



Quite recently I undertook an inquiry into the larvae of the myiasis-producing 

 Diptera of India in order to discover to what species of flies they belonged. Through 

 the kindness of the Indian Research Fund Association I was able to issue a printed 

 appeal, with detailed instructions for collecting living larvae, to every medical and 

 veterinary officer in India, Burma, Assam and Ceylon, and in a very short time large 

 numbers of living larvae and puparia were received from all over this area, and hun- 

 dreds of flies were bred out and accurately identified. The results of this inquiry 

 have demonstrated how little we know of the Indian species whose larvae cause 

 myiasis in man and animals. The following species were found to be those which 

 usually cause myiasis in man and animals in India : — 



(1). Chrysomyia {Pycnosoma) bezziana, Vill. — This proves to be the common 

 myiasis-producing Calliphorine of India and adjacent parts. Its larvae cause rhinal, 

 oral, ocular, aural, vaginal and cutaneous myiasis in man and animals, but its larvae 

 never cause intestinal myiasis. 



(2). Chrysomyia megacephala, Fabr. {dux, Esch.) and Lucilia argyricephala, Fabr. 

 {serenissima, Macq). — The larvae of both these species may be occasionally found 

 in cases of myiasis in animals. 



(3). Sarcophaga sp. incert. — This species, which it has not been possible to identify, 

 as the larvae were sent to me preserved in spirit, occasionally causes cutaneous and 

 intestinal myiasis in man. In the former cases the destruction of the tissues is very 

 extensive. 



(4183) S 2 



