42 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



The results given in table 9 show that when water extract of bean 

 leaves was compared to unsprayed leaves it was about equally attrac- 

 tive, while sweetened water extract was about 3.56 times as attractive. 

 Steam distillate from bean leaves was not attractive, but gave practi- 

 cally the same result as did water, indicating that its faint odor had 

 no attractive influence. 



(9) Chemotaxis more important tJian pJiototaxis in the finding of 

 food. Sixteen series of tests were conducted to ascertain whether 

 phototaxis or chemotaxis, or possibly thigmotaxis, is the more im- 

 portant in the finding of food. Squares of bean leaves, apple leaves, 



Table ii. — Tests to determine ivhettier repellents zvould protect beans from the 



Mexican bean beetle 



T3tl 



■a ° 



Unsprayed (control).. 



Tar and lime 



Nicotine sulphate and 



lime 



Derris product 



Unsprayed (control).. 



Cresol 



Nicotine sulphate .... 

 Beta naphthol 



226 

 216 



196 

 120 



256 



251 

 219 

 142 



7.06 ± 0.49 

 6.75 ±0.53 



6.12 ± 0.47 



3.75 ±0.47 

 8 . GO ± o. 64 



7.84 ±0.49 

 6.84 ±0.56 

 4.44 ±0.47 



Sept. 9 



Sept. 10 



32 



32 



and rriulberry leaves, all of the same shai>e and size (i in. square), 

 but some bearing a film of cane sugar, represented practically the 

 same color, form, and texture, but differed chemotactically. Cotton 

 wet with green water and with green sugar water (a green dye being 

 used) also somewhat resembled the leaves in color but differed in 

 other respects (table 10). 



The results given in table 10 show that sweetened food is preferred 

 to non-sweetened food and that chemotaxis is more important than 

 phototaxis in bringing about the results obtained. 



(10) Repellents zvould probably not protect beans. — To ascertain 

 whether certain substances, usually known as repellents, would keep 

 the beetles away from the treated leaves in the four small cages, 

 bean foliage was sprayed with the following : Tar and lime, combined 

 as a dust ; nicotine sulphate and lime, combined as a dust, a com- 



