194 



BuLivETiN 87 



damage. The only remedies which can be suggested consist in 

 making observations to determine where the insects are breeding 

 and in destroying them by spraying with coal oil or by burning 

 whenever they are found concentrated in considerable numbers. 

 If they have appeared in the cotton fields the only remedy available 



consists in hand picking. Each adult 

 of this species is capable of destroying 

 from two to five cents worth of cotton 

 lint and it is unquestionably very 

 profitable to collect them by hand 

 when this work can be done at a slight 

 cost, as for instance 10 or 15 cents a 

 hundred. 



Fig. 20. — The brown cotton bug. 



Fig. 21 — The difEerential grasshopper, 

 natural size.) 



(About 



GRASSHOPPERS 



Three species of grasshoppers have been observed doing dam- 

 age to cotton in Arizona. The attacks of these insects in large num- 

 bers may result in the complete destruction of the crop. In several 

 instances noted the plants have not only been completely stripped 

 of all leaves but the green bark has been gnawed from the main 

 stem and branches., Grasshoppers in cotton growing sections 

 breed principally in alfalfa fields and are very apt to migrate from 

 the alfalfa to cotton immediately after a heavily infested crop of 

 alfalfa is cut for hay and removed from the field, particularly when 

 the cutting and raking is started on the side away from the cotton 

 and these and other cotton pests are virtually driven out. The prin- 

 cipal grasshopper damage to cotton in Arizona is by a species 

 known as the dififerential grasshopper (Mclanophis differ entialis 

 Thos.) This insect is light brownish in color with black markings. 

 The adult females are over an inch and a half in length. The vo- 

 racity of these insects is indicated by a calculation made by the 

 writer showing that when the adults average about 16 to a square 



