NO. 1 8 



SENSE ORGANS OF COLEOPTERA — McINDOO 



41 



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

 arranged Hkewise at the other end of the cage. 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 exi^eriment was ended, the sweetened leaves 

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



Table 10. — Tests to determine ivhether chcmotaxis or phototaxis is more 

 important in the finding of food by Mexican bean beetles 



O-.-O 

 m M CT 



Beau leaves, not 

 sprayed (control). 



Apple leaves not 

 sprayed 



Green water on cot- 

 ton 



Green sugar water (i 

 to 25) on cotton. . 



Bean leaves, not 

 sprayed (control). 



Mulberry leaves not 

 sprayed 



Mulberry leaves, 

 sprayed with sugar 

 water ( i to 25 ) . . . 



Bean leaves, sprayed 

 with sugar water 

 (i to 25) 



68 



4 

 196 



63s 

 116 



19 

 7Z 



2.12 ± 0.31 

 0. 12 ± 0.02 

 6.12 ± 0.76 

 19.84 ± 0.99 

 3.62 ± 0.24 

 0.59 ± O.II 



2.28 ±0.30 



6.91 ±0.42 



0.06 

 2.88 



9-34 

 1. 00 

 0.16 



0.63 



1.90 



Sept. 23 



Sept. 24 



32 tests. 

 Beetles 

 in direct 

 sunshine. 



2,2 



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 teslcd.~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). 



