THE CANADIAN ENTOMOLOGIST 



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caught up with the other poisons within two and one-half days. 

 Arsenate of lead was much slower than any of the four poisons 

 mentioned above, although ultimately, that is at the end of five 

 or six days, was more effective than the other poisons, although it 

 must be remembered that the arsenate of lead bait was used twice 

 as strong as the other poisons. Arsenous acid (white arsenic) 

 gave the poorest results, for it was not only much slower in action 

 but its accumulative effect was inappreciable. 



Summarizing our results with poisons we can conclude that 

 Paris green, crude arsenous oxid and sodium arsenite are the 

 mere desirable for poison baits, while calcium arsenate is next in 

 value. Our results indicate that lead arsenate should only be 

 used when one of the four poisons mentioned above are not avail- 

 able, and then it must be used at a strength of about 1-20. Our 

 results with arsenous acid are wholly negative. 



Table 3. Results from use of varying mixtures. 



Various experiments were made to determine the effective- 

 ness of bait prepared in different ways. That is, bait where lemon 

 extract was used in place of lemon fruit; and with and without 

 molasses. There was no great difference between baits prepared 

 with bran, lemon extract and molasses; bran, lemon fruit and 

 molasses; bran and lemon extract; bran and lemon fruit; bran and 

 molasses and bran and bananas. However, i'n all of the experi- 

 ments where lemon extract was used in comparison with lemon 

 fruit, the extract gave a higher percentage of effectiveness, and 

 these experiments, although carried on in the laboratory, seem to 

 be sufficiently conclusive to warrant the use of lemon extract in 



