Insect Pksts of Intkrest to Cotton Growers 



191 



on the immature bolls. By means of delicate, threadlike parts of 

 the mouth organ known as setae the bug- punctures the carpel of 

 the boll and the seed coat, and sucks the juices from the inside of 



the seed. This results in an abnormal 

 growth or proliferation being produced 

 on the inside of the carpel at the point 

 of entrance of the setae and in the 

 decay of the attacked seed and sur- 

 rounding lint. There is no mark on 

 the outside of the boll to indicate this 

 internal injury. In the West Indies in- 

 vestigations have shown that a similar 

 decay is caused by a fungus which is 

 supposed to be introduced into the interior of the bolls by sucking 

 bugs, principally cotton stainers. It is probable that the internal 



Fig. 17 — Southwestern cotton 

 stainer. Female at left, male at 

 right. (About natural size). 



Fig. 18— Work of cotton stainer. -One lock shrivelled and decayed. 



decay of cotton bolls which occurs in the United States is also due 

 to a fungus introduced by sucking bugs. 



The Southwestern cotton stainers are not generally injurious 

 throughout the Salt River Valley, but in one locality during the 



