Apr. 15, 191S 



Overwintering of the House Fly 



153 



Table II. — Longevity of house flies during the -winter, in a heated room in a greenhouse 



Experi- 

 ment No. 



Flies 

 emerged. 



Remarks. 



M-4. 

 M-5. 



M-6. . 

 M-8.. 

 M-ii. 



M-14. 



M-17. . 

 M-18.. 

 M-21. . 



5-A5. 



5-A6. 



5-Bi. 

 5-B2 . 



5-B3 . 

 ii-Ai 



1914. 

 Nov. 18 



Nov. 19 



Nov. 21 



Nov. 28 



Dec. 2 



Dec. 30 



1915- 



Feb. 7 



Feb. 26 



Mar. 3 



Nov. 7 



Dec. 4 



Dec. 9 



Dec. 13 



Dec. 16 



Nov. 25 



Fungus appeared on sixth day after emergence, 



and killed all fiies. 

 Two dead on third day. Fungus appeared 



first on eighth day after emergence, and 



killed all remaining flies. 

 Fungus first appeared on sixth day after 



emergence. 

 Fungus appeared first on sixth day after 



emergence, and was cause of all deaths. 

 Fungus appeared on eighth day and caused 



all subsequent deaths. 



No deaths from fungus, although the cage had 

 previousl}^ held diseased flies and had not 

 been disinfected. 



No fungus noted . 

 Do. 

 Do. 

 Fungus first appeared on tenth day, and was 



cause of all deaths. 

 Fungus appeared on the sixth day and was 



cause of all deaths. 

 Fungus appeared on the foitrteenth day. 

 Fungus appeared on the tenth day. 

 No fungus noted . 

 Severe fungus attack, beginning on sixth day 



after emergence, was cause of all deaths. 



Incidentally the experience with Etnpusa muscae in these experi- 

 ments brought out the following points: (i) All the flies which emerged 

 before December 30, with one exception (see lot No. 5-B3, Table II) 

 were attacked by the fungus. All the lots of flies which emerged after 

 December 30 gave no evidence of fungus attacks, although kept under the 

 same conditions in cages which, earlier in the year, had held diseased 

 flies, and which subsequently had not been disinfected. (2) The short- 

 est time between the emergence of the flies and the first death from 

 Empusa muscae was 6 days, but all were not affected at the same time; in 

 some cases the period being extended to 19 days. It was found possible 

 to obtain eggs from nearly every lot of flies before the fungus finally de- 

 stroyed them. Even if it were possible to propagate Empusa muscae 

 artificially and to disseminate the spores where they would be taken up 

 by flies, it is doubtful whether it v.^ould be entirely effective, since, as 

 the records show, eggs were often obtained before all the flies had been 

 killed. (3) Experiments with the house fly do not support Dove's theory, 

 based on experiments with Lucilia, that the fungus develops principally 

 in sexually mature and in fertilized flies, which do not oviposit on account 

 of low temperatures or in the absence of media for deposition. 



