HOW INSECTS AFFECT THE COTTON PLANT 

 AND MEANS OF COMBATING THEM. 



How cotton attracts insects 3 



How insects may be controlled before plant- 

 ing 4 



Posts that menace the stand of seedling cotton -1 



I njuries which abort the growth 7 



Injuries to the gi-owing tip 9 



Leaf injuries and defohation lo 



CONTENTS. 



I*ag3 



How insects reduce 1 he yield k; 



Injuries to the stalk and roots 22 



Insects in decayed and dry bolls 24 



The double role of ants 24 



The parasites 25 



Insect visitors of cotton 26 



Smiiinary of control measures 26 



HOW COTTON ATTRACTS INSECTS. 



NOT ONLY the squares and bolls of cotton, but the leaves and 

 flowers are attacked by insects, and many species attack the 

 stems and roots. In addition to the attraction of the plant to those 

 insects which require it as food, the cotton plant is supplied with a 

 peculiar means of attracting insects. On the underside of cotton 

 leaves, on the midrib, or princi|)al vein, and sometimes also on two 

 other veins, one can find a little elongate depression which usually 

 looks sticky and often holds a drop of liquid. On the outside of the 

 squares at the base of each bract or leaflet are other little cups and 

 between the bract and the bud itself are tlii-ee more cups. At the 

 bottom of the flower cup still others of these little vessels are found. 

 They are called nectar cups, or nectaries, because they exude a sweet 

 liquid. Tliis hquid is greatly desired by many insects, beneficial 

 and harmful, and is the means of attracting to the cotton plant a 

 great variety of insect life. 



As' a result of the peculiar attractiveness of cotton for insects many 

 specimens of harmless insects collected at the nectar are sent to 

 entomologists under the impression that they are dangerous pests. 



It would be impossible in a pubhcation of this series to mention 

 even briefly all of the cotton pests. The main object is to explain 

 how insects affect the plant and to show how to distinguish the 

 principal ones and how to combat them. The more im])ortant 

 species, like the boll weevil and the bollworni, are Irciil cd fully in 

 other publications.' 



> See Farmers' Bulletin 848, "The Boll Weevil Problem with Special Keference lo Means of Reducing 

 Damage," and Farmers' Bulletin 872, "The Bollworm or Corn Earworm." These may be obtained free 

 from the Division of PubUcations, U. S. Department of Agriculture. 



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