104 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 10 



carefullj^ washed at the conckision of each experiment. All solutions 

 were made with distilled water. 



The traps were placed in a linear series along the shelf three feet 

 apart. Special care was exercised that no trap contained the same 

 material or occupied the same position in the series in two consecutive 

 experiments. Unless otherwise stated only one portion of a substance 

 was used in each test. 



The results given apply only to the house-fly {Musca domestica L.) 

 which made up more than 95 per cent of the catches during the 

 summer. 



Experiments with Carbohydrates 



Because of the prevalence of carbohydrates in foods to which the 

 house-fly is attracted, it was decided to test them rather thoroughly. 

 Glucose (dextrose) , fructose (levulose) and galactose were chosen from 

 the monosaccharides; maltose, lactose and sucrose (cane sugar) from 

 the disaccharides; and dextrin and starch from the polysaccharides. 

 Solutions of 1 gram, 2 grams and 5 grams to 50 cc. of water were em- 

 ployed and 50 cc. were placed in each trap. The experiments with 

 galactose were not completed owing to the difficulty of obtaining this 

 compound. The results are expressed in the following table: 



ExPBEIMENTe ON CARBOHYDRATES 



1 Two traps used in experiment. 



On the whole these carbohydrates in aqueous solution were not 

 very attractive to house-flies. Considering all the experiments, 

 lactose caught the largest number of flies (204), starch the least (12). 

 Dextrin also caught a comparatively large number of flies (135). 

 Sucrose was consistently a poor bait, catching but 26 flies in six experi- 

 ments. From the foregoing tests, I believe it can be safely stated 



