THE CANADIAN ENTOMOLOGIST 



189 



Table 1. Value of substitutes for bran in poison bait. 



It is thus evident that bran is noticeably superior to sawdust 

 alone and even the combination of sawdust and bran, but these 

 laboratory experiments in connection with the field experiments 

 at Johnson and Akron, Indiana, show that sawdust does have 

 some value and can be recommended where it is impossible or very 

 difficult to obtain bran but where it is used, a second application 

 will probably be necessary and a combination with some bran 

 which will prevent the mixture from scattering into too fine par- 

 ticles and drying quickly, is preferable. 



Three kinds of sawdust were used: viz.. old hardwood (oak 

 and hickory), new hardwood (hickory) and pine. The pine saw- 

 dust seemed to have a decided repellant effect and should not be 

 used as a filler for the poison bait. In comparing new and old 

 hardwood sawdust we found a larger percentage killed where 

 the new was used, but our comparative tests with these materials 

 are not sufficient to draw satisfactory conclusions. The new hard- 

 wood (hickors') was used in all experiments in comparison with 

 bran. 



The most important data obtained was a comparison between 

 Paris green and other arsenicals. In the total number of experi- 

 ments where Paris green was used, 16 in number, we killed 75.8% 

 while calcium arsenate in 5 experiments killed 70%; sodium- 

 arsenite in 4 experiments killed 80.8%; lead arsenate in 3 experi- 

 ments, 85.8; arsenous acid (white arsenic) in 2 experiments gave 

 20.8%, and crude arsenous acid, a by-product of copper refineries 

 which contained 88% of arsenous oxid, killed in 14 experiments 

 74.4%. It might be stated that these materials were used 1 lb. 

 to 40 of filler, excepting in one experiment with crude arsenous 

 oxid and one experiment with arsenous acid where it was used 

 1-25, and in all three experiments with lead arsenate where it 



