NO. 1 8 



SENSE ORGANS OF COLEOPTERA — McINDOO 



41 



gether in one end of a cage, and the other two sprayed plants were 

 arranged likewise at the other end of the eage. Soon after placing 

 100 beetles in the cage the insects climbed upon the sprayed foliage, 

 paying apparently no more " attention " to the sweetened leaves than 

 to the non-sweetened ones, but after a few hours and thereafter until 

 October 3, when the experiment was ended, the sweetened leaves 

 bore the more beetles and were the more eaten. The final result 



Table 10. — Tests to determine ivhcthcr chemotaxis or phototaxis is more 

 iviporlant in the finding of food hy Mexican bean beetles 



showed that the sweetened leaves bore 69.7 per cent of all the beetles 

 counted on the four sprayed plants. 



(8) Water extract and steam distillate of bean leaves tested. — To 

 test the diluted juice of bean foliage, a water extract was prepared by 

 adding 50 cc. of water to 10 gm. of leaves, cut into small pieces. After 

 macerating the pieces and decanting the liquid through cheesecloth, 

 50 cc. of a greenish liquid was secured. To test the steam distillate 

 of bean foliage, 100 cc. of water was added to 30 gm. of leaves, cut 

 into small pieces, and then 50 cc. of a clear and odorous distillate was 

 collected (table 9). 



