192 Bulletin 87 



year 1916 they were destructive on several farms, destroying" from 

 50 to 75 percent of the immature bolls. In one section of a cotton 

 field comprising four or five acres it was estimated that the insects 

 had destroyed fully 90 percent of the bolls. 



In addition to the complete destruction of young bolls cotton 

 stainers do much damage by attack on bolls which are mature or 

 nearly so. When such bolls are attacked the injury appears in the 

 form of stained lint. In one instance observed by the writer the 

 Florida cotton stainer damaged a crop of about 1000 bales of Sea 

 Island cotton to the extent that 200 bales were classed as stained. . 



The Southwestern cotton stainers were not present in injurious 

 numbers in any part of the Salt River Valley during 1917 and 1918. 

 They may be expected to vary greatly in numbers from year to 

 year. They should be recognized by all cotton growers as being 

 capable of causing considerable damage. Whenever any are found 

 they should be watched carefully and whatever steps may be neces- 

 sary should be taken to prevent breeding on weeds or other plants 

 in the neighborhood of cotton fields, while in the cotton fields the 

 stainers should be collected and destroyed whenever they appear 

 in threatening numbers. The bugs have a habit of congregating 

 in large numbers on the bolls, and their conspicuous color makes it 

 easy to destroy them by knocking them by hand into a bucket or 

 other convenient vessel containing water with a small amount of 

 coal oil on the surface. 



THE BROWN COTTON BUG 



A third species of plant bug which has caused noticeable dam- 

 age to cotton in Arizona is known as the brown cotton bug (Buschis- 

 tus impictiventris Stal.) This is very closely related to the brown 

 cotton bug which is known as a cotton pest in Texas and other 

 states of the cotton belt. This insect belongs to the group com- 

 monly known as "stink bugs". The adult is broad and flattened, a 

 little over half an inch in length, has rather sharp shoulders and is 

 yellowish below and marked with dark brown or black punctures 

 above. The brown cotton bug injures the crop by sucking the 

 juices from the bolls. The thread-like mouth organs are used to 

 . penetrate through to the interior of the developing seed. The effect 

 is similar to that produced by the cotton stainer. The brown cotton 

 bug is found in nearly all cotton fields in Arizona, sometimes in 

 considerable numbers. No excessive damage, however, has thus 

 far been observed. The importance of this pest consists in its gen- 



