CACTUS SOLUTION AS AN ADHESIVE. 



9 



This plant began to wilt and appear blighted on April 18, little 

 feeding being done from that date, even though the poison had been 

 on the plant for nearly two weeks. It is thought that a higher mor- 

 tality would have occurred had the plant remained green and living. 



An arsenate of lead spray was made, using the paste form at the 

 rate of 4 pounds to 60 gallons of water. In this solution no cactus 

 was used. On April 11 five beetles were placed on an encaged cab- 

 bage plant in the insectary that had been sprayed five days before. 

 Table XI gives the final results. 



Table XI. — Experiment No. 20. — Arsenate of lead without cactus, Brownsville, 



Tex., 19U h 



Date. 



Apr. 13 

 Apr. 14 

 Apr. 16 

 Apr. IS 



Beetles 

 present. 



Living. 



Dead. 



Feeding. 



Not feed- 

 ing. 



This spray did not adhere to the cabbage foliage as well as when 

 cactus was used, and the beetles fed very slowly after the first two 

 days of confinement. Better results were obtained in the field, as 

 the beetles began feeding just after spraying, and where a partial 

 uniform coating was secured the poison was effective. If the poison 

 could be made to combine or mix with cactus water the results would 

 undoubtedly be much better. 



April 2 a solution was made up of iron arsenite, using 1 pound 

 to 40 gallons of water. Some difficulty was experienced in bringing 

 the poison into suspension, as it settled quite rapidly to the bottom 

 of the barrel. April 4 another solution was prepared, using the 

 same amount of poison to a given quantity of water, with the pre- 

 vious addition of cactus at the rate of If pounds to each gallon of 

 water, in which salicylic acid had been used as a preservative to 

 prevent fermentation of the cactus juice. As a check some potted 

 cabbage plants were spraj^ed. On April 11 ten belted cucumber 

 beetles were encaged on one of the cabbage plants that was sprayed 

 April 4. Table XII gives the results. 



Table XII. — Experiment No. 21. — Cactus as an adhesive with Iran arsenite, 



Brownsville, Tex., 191Jf. 



Date. 



Beetles 



present. 



Living. 



Dead. 



Feeding. 



10 



9 





7 



8 



7 





7 



8 



7 





7 



2 



1 





1 



2 



1 









Not feed- 

 ing. 



Apr. 13 

 Apr. 14 

 Apr. 15 

 Apr. 16 

 Apr. 18 



65966°— Bull. 160— It 



