THE FLIES THAT CAUSE MYIASIS IX MAX O 



Palaearktischen Region/' edited by Erwin Lindner (Stuttgart), gives 

 keys and descriptions, with numerous illustrations, of all the 

 Palaearctic Diptera; thus far the families Sylvicolidae (as Phry- 

 neidae). Stratiomyidae, Therevidae. Syrphidae, Tylidae, Ephydridae. 

 and Drosophilidae. as well as some that contain no myiasis-producing 

 species, have been published. In the "Fauna of British India, Dip- 

 tera" (London. 1920-40), the parts pertinent to this work that have 

 been published are volume II (including the Stratiomyidae and 

 Therevidae). volume III (including the Syrphidae and Oestridae 

 in a broad sense), and volume VI (comprising the Calliphoridae, 

 including the Sarcophagidae). 



TYPES OF MYIASIS 



Two general plans have been used for the classification of myiasis. 

 The one, that of Pat ton. is based on the biological requirements and 

 responses of the fly in its various stages of development ; the other, 

 that of Bishopp. is concerned with the part of the body affected. Each 

 classification has its particular use ; Patton's is the more satisfactory 

 from the standpoint of the student, whereas Bishopp's is of more use 

 to the practicing physician and the practical medical entomologist. 



PATTON'S CLASSIFICATION 



Patton (100. 102) divides the myiasis-producing Diptera into three 

 groups. The first group, the specific myiasis-producing Diptera (table 

 1), includes those species ''whose larvae are found only in living tis- 

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

 organ, depending on the species, in which or near which to la}' their 

 eggs or deposit their larvae." This group, therefore, comprises a 

 relatively -man number of species to which the parasitic habit has be- 

 come obligatory. It also comprises the most serious myiasis produc- 

 ers from a pathogenic standpoint, since its larvae do not utilize carrion 

 or other nonliving material as an alternative breeding medium. They 

 may attack wounds, skin, or the external body openings, but never 

 the digestive tract. Members of this group are scarce as adults, in 

 comparison with carrion-breeding and other species that are not 

 strictly parasitic; and for this reason the true etiological agent and 

 the nature of its parasitism has. in several instances, remained obscure 

 until comparatively recent times. 



The second, or semispecific. myiasis-producing group (table 2) in- 

 cludes ''those flies which, though normally breeding in the bodies of 

 dead animals, and even in vegetable matter, will occasionally lay their 

 eggs, or deposit their larvae in the diseased tissues of man or animals." 

 Oviposit ion or larviposition is stimulated by foul or fetid odors; the 

 female fly will not deposit eggs or larvae on unbroken skin or on fresh, 

 clean wounds. A fetid discharge from a body opening, however, or. 

 in the case of sheep or other wooly animals, soiled wool may be a 

 sufficient attractant to the fly. The developing larvae may confine 

 their activities to necrotic tissue: on the other hand, they may invade 

 the deeper, sound tissues. Some members of this group are of little 

 importance from the standpoint of human and animal myiasis; some, 

 however, may be dangerous. 



