12 



BULLETIN 160, U. S. DEPARTMENT OF AGRICULTURE. 



On April 4 a small plat of cabbage was sprayed with iron arsenite 

 at the rate of 1 pound to 40 gallons of water. Two pounds of cactus 

 were added to each gallon and the decoction was prepared on March 

 14 and 15. It was preserved with salicylic acid at the rate of % 

 pound to 50 gallons. It was quite difficult to bring the arsenite of 

 iron into suspension. Thorough agitation was required to prevent it 

 settling to the bottom of the tank. With a hand sprayer it is impos- 

 sible to secure uniformity in the spra}^. Table XVI gives results with 

 10 beetles on one cabbage plant sprayed on April 4, the beetles being 

 liberated on the plant April 11. 



Table XVI. — Experiment No. 27. — Cactus as an adhesive with iron arsenite, 



BrownsviWe, Tex., Idllf. 



Date. 



Beetles 

 present. 



Apr. 13 

 Apr. 14 

 Apr. 16 

 Apr. 17 

 Apr. IS 

 Apr. 20 

 Apr. 21 

 Apr. 23 



Living. 



Dead. 



Feeding. 



Not feed- 

 ing. 



Feeding was very heavy on this plant, which had been growing 

 for some time in the pot and had been seriously attacked by aphides 

 on two occasions. Iron arsenite has some value as an insecticide, but 

 not as much as ferrous arsenate, even when properly made up, and 

 unless an effort is made to apply it in uniform coating on the foliage 

 it has little value as an insect destroyer. 



CACTUS COMPARED WITH WHALE-OIL SOAP AS AN ADHESIVE. 



On February 20, 1914, while conducting spraying experiments 

 against the belted cucumber beetle and cabbage looper (Autographa 

 brassicce Riley) on cabbage on the farm of Mr. George Federhoff , near 

 Brownsville, Tex., it was decided to make a comparison of whale-oil 

 soap and cactus as adhesives, without considering the cost of the 

 two products. One acre of cabbage was sprayed with 1 pound of 

 zinc arsenite (in powdered form) to 60 gallons of water, with the 

 addition of 35 pounds of cactus. The cactus was sliced and put in 

 the water on February 19, and had given up its glutinous matter 

 to the solution by the time spraying was begun the following 

 day. This mixture spread and adhered exceedingly well. The 

 next acre was sprayed with the same amount of poison, but whale- 

 oil soap was substituted for cactus. This was done both for a 

 comparison of adhesive qualities and to observe the effect of the 

 soap on the cabbage aphis (Aphis brassicce L.), as in several spots 



