372 
C, GOKDOX 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^ of its occurrence 
on Esher Common, where it had attacked a species of Syrphid, 
^lelanostomum 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 Syrphidte. This author states that Empusa 
muscie 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 ou a fly rests 
among the haii’s 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 ai’e formed, and 
falling into the blood sinus ai’e carried throughout the whole 
of the body of the fly. It was probably these bodies that 
Colin (1855) found, and he explained their pi’esence 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, Avhich 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 ai’e closely packed 
together in a palisade-like mass to form a compact white 
cushion of conidiophores, wliich is the transverse white ring 
that one finds between each of the segments of a diseased, and 
‘ ‘ Trans. Ent. Soc, London.' 1908 (“ Proceedings,” p. 57). 
