house-fly investigations. 515 



General Summary. 



The general conclusions resulting from these experiments on 

 baits and poisons for flies, show that : — 



(1) For Blow-flies, meaty substances of all kinds make the 



best baits, and of these the most attractive was blown 

 liver, several days old. It was found that the digestive 

 action of the maggots increased the attractiveness of the 

 baits. 



(2) The most satisfactory House-fly baits consisted of mixtures 



of casein, banana, and some sweet substance (^. e. treacle, 

 sugar, etc.) to which suflicient water, beer, or stout was 

 added to make a paste. 



(3) Apparently Formalin remains the best poison for House- 



flies for indoor use, in spite of its somewhat uncertain 

 action. The best results were obtained when 2*5 "j^ to 

 7*5 °/o pure Formalin was used. 



Note on Empusa mvscje. 



It is perhaps worth noting that the house-flies in the " fly- 

 room" became badly infected with the fungal disease Empusa 

 viuscce in September and October, and died in great numbers, 

 although they still continued to breed. It is interesting to note 

 that however they became infected, the disease followed its 

 usual course and subsided in November and December, when 

 " wild " flies have normally disappeared. 



Carbolic acid was evaporated two or three times a day at first, 

 and occasionally up to the end of December. 



Note on the Proportion of the Sexes in House-flies 

 {MuscA domestica). 



(1) The proportion of male and female House-flies was found 

 to be nearly equal in the various counts made on emerging flies. 

 The results are given below : — 



i. ?. 



(«) Pupae taken from manure-lieap wLich hatched out Aug. 7, 1915. 51 66 



{h) Flies emerged from pupa3 bred in greenhouse, Aug. 27, 1915 ... 52 35 



(o) D«tto, Aug. 26-30, 1915 51 102 



(rf) Ditto, Aug. 27-28, 1915 57 39 



(e) Ditto, 11 A.K. to 2 P.M., Aug. 28, 1915 60 53 



(/) Ditto, at 2.45 P.M., August 28, 1915 121 67 



ig) Ditto, at 3.30 P.M., Aug. 28, 1915 80 111 



(li) Flies emerged from pupaa from breeding-saucers Feb. 11, 1916... 31 27 



Total 503 500 



(2) Counts were also made of Flies caught in balloons and 



36* 



