196 ' Bulletin 87 



and this mixture then thoroly stirred into the bran-sawdust-Paris 

 green combination. More water is added as needed to make a 

 moist crumbly mixture. This mixture should be sown broadcast 

 in the infested cotton fields. Observations on the habits of the dif- 



Pig. 23. — Cotton plants in foreground stripped of leaves by differential 

 grasshoppers wtiich migrated from adjoining alfalfa field. 



-ferential grasshopper have shown that late afternoon is not a favor- 

 able time for spreading the bait in cotton growing sections of 

 Arizona. 



The advantages of concentrating grasshoppers and cotton square 

 <iaubers in the center of alfalfa fields rather than driving them out 

 with mowers and rakes, as is sometimes done with disastrous re- 

 sults to adjoining cotton, has been discussed under the subject of 

 the control of the cotton square daubers. Heavy applications of 

 poisoned baits in proportion to the abundance of the insects in the 

 xmcut area, or the use of the hopper dozer, are the best available 

 methods of disposing of the grasshoppers after they have been 

 concentrated. 



THE COTTON APHIS 



During the first two or three weeks in the spring after the young 

 cotton plants come through the ground cotton growers are fre- 

 quently alarmed by the attack of small greenish or greenish black 

 insects known as the cotton aphis (Aphis gossypii Glov.) The same 

 species attacks and sometimes destroys melon vines and is perhaps 

 iDetter known as the melon aphis. It occurs everywhere in the 

 XJnited States where cotton is grown, but is not ordinarily of much 



