NO. 1 8 



SENSE ORGANS OF COLEOPTERA — McINDOO 



37 



50 mg. of picric acid, quinine sulphate, or strychnine sulphate to 25 cc. 

 of water. The fourth was prepared hy adding 25 cc. of water to the 

 macerated bodies of 20 live bean beetles. The resulting liquid, when 

 filtered, was yellowish and to the writer had a bitter taste and an 

 unpleasant odor. It was sprayed upon bean leaves, which when dry 

 were cut into pieces, one inch square, then put on the pieces of card- 

 board, and finally fed to the beetles (table 4). 



Table 6. — Tests to determine ivhethcr bean foliage sprayed zvith sivcetened 



arseiiicals is more attractive to Mexican bean beetles than 



unsprayed foliage 



a rt ^ 







Unsprayed (control).. 



Calcium arsenate and 

 sugar 



Magnesium arsenate 

 and sugar 



Lead arsenate and 

 sugar 



Unsprayed (control).. 



Magnesium arsenate 

 and table molasses.. 



Magnesium arsenate 

 and corn sirup 



Magnesium arsenate 

 and black-strap mo- 

 lasses 



74 

 106 



131 



132 

 131 



194 



157 



113 



2.31 =to.35 



3.31 ±0.31 



4.io±o.33 



4.12 ±0.30 

 4. 10 ±0.38 



6 . 06 ± 0. 40 



4.90 ± 0.49 



3.53 ±0.40 



1. 00 

 1-43 



1.77 



1.78 

 1. 00 



0.86 



18 



Sept. 5 



Sept. 25 



32 



?>2 



(4) Beetles can distingiiisJi differences hctiveen zvater and sivect 

 liquids. — To determine whether the above is correct, 24 series of 

 tests were conducted by using six sweet solutions, each of five of them 

 being prepared at the rate of i gm. or i cc. of granulated cane sugar, 

 grape sugar (dextrose), a high quality table molasses, corn sirup, or 

 black-strap molasses to 25 cc. of water; and the sixth at the rate of 

 20 mg. of saccharine to 25 cc. of water (table 5). 



From the information given in tables 2 to 5, with additional notes, 

 it may be concluded that Mexican bean beetles exhibit " likes " and 

 " dislikes " when fed substances which produce the four human at- 



