162 



THE FUNGAL DISEASE: EMPUSA MUSCAE COHN 



E. americana Thaxter. E. americana attacks blow-flies and other 

 flies similar in size to the house-fly and is frequently found out-of- 

 doors. 



E. muscae, besides occurring on 31. domestica has been found 

 on several species of Syrphidae and also on Lucilia caesar and 

 Calliplwra vomitoria. 



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Fig. 73. (o) Longitudinal (sagittal) section of abdomen of ilf. domestica, which has 

 been killed by Empiisa muscae, showing the feltwork of fungal hyphae iilliug 

 the inside of the abdominal cavity and the production of conidia in the inter- 

 segmental regions, x 12. c Conidiophores producing conidia. /. FungaJ 

 hyphae. 



(h) Four conidiophores showing the formation of conidia (e). x 100 (approx.). 



(c) Conidium of Empiisa muscae. x 400. o.g. Oil globule. 



The development of the house-fly fungus Empusu muscae was 

 very carefully studied by Brefeld (1871). An Empusa spore which 

 has fallen on a fly rests among the hairs covering the insect's bod}' 

 and there adheres. A small germinating hypha develops, which 

 pierces the chitin, and after entering the body of the victim pene- 

 trates the fat-body. In this situation, which remains the chief 

 centre of development, it gives rise to small spherical structures 

 which germinate in the same manner as yeast cells, forming 

 gemmae. These separate as they are formed, and falling into the 

 blood sinus are carried throughout the whole of the body of the 

 fly. It was probably these bodies that Cohn (1855) found, and he 



