146 



OLIVE C. LODGE. 



Table III. — cont. 



Bait, 



Musca. 



Colli, 

 phora. 



Lucilia. 



Phormia 



Sarco- 

 phaga. 



Fannia. 



Oil of verbena 



1 



, 







2 



__ 



__ 



Palma rosa 





1 























Peppermint 





1 







2 



1 



. — 







Control 





2 





. — 



— 



— 







Heliotrope 





1 









— 











Citronella 





1 







3 



— 



1 







Camphora 





1 



4 



1 



1 



— 



1 



Santal 













1 



r 



— 







Cassia 

















2 











Java citronella. . 





























Sassafras 





0-5 











1 











Cummin 









1 







.— 







. — 



Geraniol 

















— 











Anisol 





























Cinnamon bark 





























„ leaf 









— 



— 



— 



— 







Ceylon citronella 









— 



- — 



[9] 











Lavender 









1 



4 





— 



— 



Control . . 





many 



6 



7 



— 



. — - 



— 



SJ • • • • • 





2 



10 



10 



— 



— 



— 



9> . . ■ . ■ 





— 



9 



8 













Camphor 





— 



4 













2 



Honey . . 







4 



4 



3 



= 



2 



Effects of colours on flies. 



A large number of experiments were made in order to see whether the flies showed 

 any special preference for a particular colour or colours. Their colour- preference 

 was tested by means of coloured foods, coloured light, and coloured materials. 



Amongst the various ways of colouring the baits that were tried, the most 

 satisfactory one was to mix them with powdered chalks of different colours (i.e., 

 red, blue, orange, green, white, yellow and purple). It was thus possible to compare 

 the effect of the different colours under the same conditions, without any compli- 

 cations due to the effect of the different colouring matters employed, as was the 

 case when various stains, etc., were used as colouring agents.* 



In these experiments the different coloured chalks were thoroughly mixed into 

 the baits, which consisted of honey, or mixtures of casein, sugar, banana and water. 

 They were then fed, singly or in pairs, in all possible permutations and combinations, 

 to flies confined in glass cylinders, and to free flies. In some of the experiments, 

 however, baits of all colours were introduced into the cylinders at the same time. 

 They were kept under as continuous observation as possible, and the numbers of 

 males and females feeding upon the different colours were counted at intervals during 

 the day. The flies were as a rule driven off after each count. 



Controls consisting of the same number of ca*sein or honey baits, uncoloured, were 

 fed in the same permutations and combinations. It was thus possible to compare 

 the results, and the numbers feeding on the different colours, with those feeding 



*When the baits were coloured by stains, etc., methylene blue, eosin, red lead, white 

 lead, and lead chromate, were amongst those found to be very attractive, while cochineal 

 and picro-nigrisin were very distasteful to house-flies. 





