16 



FARMERS BULLETIN 890. 



the plants with arsenate of lead, but they will not be serious if proper 

 attention is given to surrounding vegetation on which they feed 

 normally. 



HOW INSECTS REDUCE THE YIELD. 



Naturally the most serious injury to the cotton crop is that which 

 affects the squares, flowers, and bolls, and among the insects causing 

 this injury are some of the most serious known insect pests. 



COTTON-BOLL WEEVIL.i 



The worst cotton pest in this country, and probably the most de- 

 structive cotton insect in the world, is the Mexican cotton-boll weevil 

 (figs. 17, 18), which annually takes a toll of tens of millions of dollars 

 from the cotton industry. As this insect is of such great importance, 

 many bulletins have been written about it, and the most recent of 

 these may be obtained on application to the Division of Publications, 



United States Depart- 

 ment of Agriculture, 

 Washington, D. (\ 

 The boll weevil lays 

 its eggs in the squares 

 and boUs. Generally 

 the squares wliich have 

 been attacked will fall 

 to the ground in a few 

 days. They always 

 flare and often hang 

 and dry on the plant. 

 The eggs hatch into 

 small white grubs, or larvte, with yeUowish-brown heads. These 

 feed in the square or boll and grow mitil they are half an inch long. 

 They usually are curved and are legless. Wlien full grown the grub 

 forms a hard cell and turns into a pupa, which matures in about three 

 days into the adult weevil. 



The weevil is easih" detected in a field. If a square is found with 

 its bracts flared and showing a little wartlike ]>uncture, it can be put 

 into a tumbler and covered with cheesecloth. After 2 or 3 days the 

 white larva can be easily found, and in about 10 or 12 days the full- 

 grown weevil will come out. 



The control of the weevil is brought about by early planting, selec- 

 tion of the best local varieties, intensive cultivation, early picking 

 of the crop, and destruction of the cotton plants, or at least destruc- 

 tion of the green growth, before frost. All of these methods will 

 also help in controlling the other cotton pests. 



' Anthonomus grandix Boh. 



-Adult female boll wee\il with wings spread, 

 larged. fHimter and Pierce.) 



