Vol. 50 No. 10 
BULLETIN 
OF THE 
TORREY BOTANICAL CLUB 
OCTOBER, 1923 
Resting spores of Empusa Muscae 
Bessie GOLDSTEIN 
(WITH PLATE 19) 
INTRODUCTION 
The parasitic fungus, Empusa Muscae, like its host Musca 
domestica, has been found in most parts of the world—Europe, 
Africa, North and South America. Great numbers of flies are 
killed every fall in Europe and this country by thisfungus. The 
possibility that such a natural parasite of the house fly as 
Empusa Muscae might be useful in combating its host has always 
made the study of this fungus attractive. 
One of the problems which has attracted the most attention 
relates to the method of wintering of the parasite. Most of its 
congeners among the Entomophthoreae winter as some form of 
resting spore in the dead body of the host. So far the only report 
of such spores in E. Muscae was made by Winter in 1881. Bre- 
feld, whose studies of the fungus and its relations to the fly are 
by far the most complete, concludes that E. Muscae does not 
form resting spores, disregarding Winter’s observations as 
inconclusive. 
Cohn, in 1885, was the first to study this disease of house 
flies in detail. He observed that flies dying of the disease at- 
tached themselves by their proboscides to window panes or 
other objects and here died of convulsions (‘unter schweren 
Kampfen”). The legs after death are spread out as in life and 
not curled under the body as is the case when death occurs 
naturally. The abdomen is swollen and often reflexed. He 
observed, too, that soon after death whitish rings of fungous 
(The BuLLErin for September (50: 283-316. pl. 15-18) was issued October 
23, 1923.1 
317 
