144 OLIVE C. LODGE. 



were kept under as continuous observation as possible for one or more days, during 

 which time counts were made at intervals of the number of males and females which 

 were feeding, or which had died during the experiment. 



The results showed that although many of the substances attracted a certain 

 number of flies, yet none of them were so attractive that all the flies present went 

 to them. Sodium iodate showed the greatest possibilities of being a good poison, 

 if it were not for the expense ; for when quite small quantities were mixed with 

 the baits and the flies fed upon them, they died very quickly — in some cases 99 

 per cent, were dead in 21 hours. It was found however that the flies apparently 

 fed upon baits containing sodium iodate only when they were very hungry, or 

 when no other more attractive foods could be obtained. The results from the 

 experiments with sodium iodate are given below in Table II. It was also tested 

 against similar amounts of formalin, when very many more flies died than with 

 the latter. 



The substances were mixed with 20 c.c. of water and then added to 10 grms. of 

 a mixture containing equal parts of casein, sugar and banana. The counts of dead 

 flies were made 21 to 22 hours after the baits had been exposed. 





Table II. 





Sodium iodate. 







Formaldehyde (40 per cent.). 



2 grms. . . 



90 per cent. dead. 



2 c.o. 



42 per cent, dead 



1 



"" >5 >> 



1 „ 



. . u ,, ,, 



0-5 , 



"*? ,» »» 



0-5 „ 



• • • • ^ ,, ,, 



0-4 „ .. 



"" >> J, 







0-2 , 



79 







The results with mineral and tar oils further confirmed the importance of oils 

 for use as repellents ; they still appear to be the substances which house-flies dislike 

 most. In the experiments made none came near any of the baits to which a few 

 drops of these oils had been added. 



The essential oils, also, were on the whole repellent to the different flies, although 

 their degree of distastefulness varied according to the species, and also with the 

 length of time of exposure. The distastefulness was found to be greatest at first ; 

 in many cases it had quite disappeared after the preparation had been left out for a 

 number of hours. 



The oils of cloves, geraniol, cummin, sassafras and cinnamon bark were found 

 to be the most repellent to house-flies. 



In Table III will be found a comparison of the relative attractiveness of the different 

 substances for the different species, summarising the results obtained in the foregoing 

 experiments. 



It is seen that the tastes of the different species are not identical, though in many 

 cases the same substances are liked or disliked by them, this is especially noticeable 

 with regard to oils and distasteful substances. 



In these experiments 2 grms. or 2 c.c. of the substances were added to 20 c.c. of 

 water and then mixed with the control bait (equal parts of casein, brown sugar and 

 banana) so as to make a paste, except in the case of essential oils, of which a few 

 drops only in water were added to the bait. 



