OCCURRENCE OF iJMPUSA OUT-OF-DOORS 



161 



end of October and usually occurs indoors. Howard states that 

 the epidemic usually ceases in Washington, U.S.A., in December. 

 Its distribution almost coincides with that of the house-fly and it 

 is the only species of Empusa which has, as yet, been recorded 

 from the southern hen^isphere. While it is uncommon out-of- 

 doors, I have found specimens of Mvsca domestica killed by it out- 

 of-doors in Canada, at Ottawa. It has been recorded diit -df-di K)rs 

 in England where it was found attacking a species of Syrphid, 



Fi(i. 72. M. doiiu'stica killed by Einpiisn iniiscae, showing discharged spores 

 (conidia). (Photo by H. T. Giissow.) 



Melanostoimim scalare Fabr. on Esher Common^ Thaxter (1888) 

 also mentions two cases of its occurrence out-of-doors in the 

 United States, in both of which cases it had attacked species of 

 Syrphidae. The same author states that Empusa niuscae is prob- 

 ably the only species which occurs on flowers attractive to insects, 

 but he only observed it on flowers of Solidago and certain Umbel- 

 liferae. He also records two other species of Empusa attacking 

 the house-fly, namely, E. sphaei^o-sperma (Fres.) Thaxter and 



^ Trans. Ent. Soc. London, Proceedings, p. .57, 1908. 



H. H.-F. 



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