200 



Bulletin 87 



skins attached to the cotton stalks if they had been breeding in num- 

 bers capable of accomplishing results." 



The feasibility of spraying for the control of the cotton aphis on 

 plants from 3 to 3>4 feet high was demonstrated at Yuma by Mr. 

 Lauderdale with an improvised power sprayer and spray boom ar- 

 ranged for spraying 5 rows of cotton at a time. He found that 

 about thirty acres of cotton could be sprayed in a day by two men 

 at a cost of about $1.25 per acre for materials. The total cost per 

 acre should be less than $1.90. The insecticide used was nicotine 

 sulfate (Black Leaf 40) and soap. The sprayer used by Mr. Lau- 

 derdale is shown in the frontispiece. 



THE COTTON THRIPS 



The cotton thrips (Thrips arizonensis n. sp. Morgan) is a slender 

 yellowish insect which when full grown is scarcely over a fifth of 

 an inch in length. It attacks young seedling cotton plants and is 

 capable of doing much damage. Characteristic effects upon the 



Fig. 2S — Work of cotton thrips on seedling cotton plant. 



