42 COTTON 



titles of petroleum to the water used for irrigation 

 might assist in the destruction of the pest. 



Cotton aphis. The cotton aphis (Aphis gossypii) 

 attacks the young plant and appears in great numbers 

 on the leaf-buds and newly-opened leaves. It some- 

 times causes considerable damage by Bucking the 

 sap from the young leaves, but healthy and rapidly 

 growing plants can usually withstand the attack. 

 The common ladybirds and their larvae feed upon 

 these insects and thus diminish their numbers to 

 some extent. 



The best remedy is the application of soap and 

 kerosene emulsion. This mixture is prepared by 

 dissolving half a pound of soft soap in one gallon of 

 boiling water, and pouring the hot solution into two 

 gallons of kerosene, and beating it up to a creamy 

 liquid. It is then made into a fairly permanent 

 emulsion by forcing it through a fine spray nozzle 

 into another vessel. This emulsion after dilution 

 with ten to twenty times its volume of water is sprayed 

 on to the infested plants. 



Cotton stainers. The large cotton stainers (Dysder- 

 cus spp.) are found in many countries in which cotton 

 is grown. In the early part of the season, the insects 

 attack the buds or young bolls and suck the sap 

 from them so that they cannot develop satisfactorily. 

 Later generations infest the open bolls, puncture the 

 seed, and stain the cotton with their yellow excre- 

 ment. The best remedial measure is to place heaps 

 of cotton seed or sugar-cane on the ground to which 

 large numbers of the insects will be attracted and 

 can then be destroyed by the application of kerosene 

 or boiling water. 



The lesser cotton stainers (Oxycarenus spp.) do 

 not occur in America, but several species have been 

 observed in Africa and two in India. In Egypt, 

 although the pest is chiefly noticeable in its attacks 

 on damaged bolls, it is often the cause of boll- 

 shedding in the early stages of growth, its punctures 

 being apparently toxic. The insects feed on the 

 unripe seeds. The stains on the cotton are not 

 produced during the life of the pest, but are due to 



