131) 



372 C. GORDON HEWITT. 



insect attacked. In this country it may be found from about 

 the beginning of July to the end of October, and usually 

 occurs indoors. It appears to be very uncommon out-of- 

 doors. A case has been recently recorded 1 of its occurrence 

 on Esher Common, where it had attacked a species of Syrphid, 

 Melanostomum scalare Fabr. Thaxter (1888) also 

 mentions two cases of its occurrence out-of-doors in America, 

 in both of which cases it had attacked, singularly enough, 

 species of Syrphidse. This author states that Empusa 

 muse as is probably the only species which occurs in flowers 

 attractive to insects, but he only observed it on the flowers of 

 Solidago and certain Umbellifereae. 



The development of this species was studied by Brefeld 

 (1871). An Empusa spore which has fallen on a fly rests 

 among the hairs covering the insect's body and there adheres. 

 A small germinating hypha develops, which pierces the 

 chitin, and after entering the body of the victim penetrates 

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

 centre of development, it gives rise to small spherical struc- 

 tures 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 

 Colin (1855) found, and he explained their presence as being 

 due to spontaneous generation ; he believed that the fly first 

 became diseased and that the fungus followed in consequence. 

 After a period of two or three days the fly's body will be 

 found to be completely penetrated by the fungus, which 

 destroys all the internal tissues and organs. The whole 

 body is filled with the gemmae, which germinate and produce 

 ramifying hyphae (fig. 15). The latter pierce the softer 

 portions of the body-wall between the segments and produce 

 the short, stout conidiophores (c.), which are closely packed 

 together in a palisade-like mass to form a compact white 

 cushion of conidiophores, which is the transverse white ring 

 that one finds between each of the segments of a diseased, and 

 1 ' Trans. Ent. Soc. London,' 1908 (" Proceedings," p. 57). 



