HOW INSECTS AFFECT THE COTTON PLANT. 7 



OTHER PESTS THAT INJURE SEEDMNGS. 



Many other pests from time to time seriously affeet stands of seed- 

 ling cotton in various parts of the country. Occasionally an early 

 grasshopper outbreak occurs. In i)arts of Alabama and Mississippi 

 cotton stands frequently are destroyed in a night by crayfish colo- 

 nies. These creatures are not insects, but })eloug to th(> class of ani- 

 mals called Crustacea, which includes the crabs aud l()])stei's. As 

 they occur only where there is a considerable amount of water under- 

 ground, their control is largely a matter of drainage. They live in 

 colonies in a large chamber at the water level and reach the surface 

 of the ground by long "chimneys." The plachig of about an ounce 

 of carbon disulphid in each "chimney," its opening thereupon being 

 closed, will kill the hmiate. Crustaceans of another group which 

 injure cotton seedlings are the sowbugs and pill ])ugs.^ They can be 

 controlled readily by poisoned liaits. 



INJURIES WHICH ABORT THE GROWTH. 



COTTON APHIS.- 



One of the earliest insects to be* found on tlie plant is the cotton 

 aphis or "cotton louse " (fig. 5), which also attacks many other plants. 

 The green "lice" are not conspicuous, but the rate of multiplication 

 is so rapid that they can become a very serious pest. They suck the 

 juices of tlie plant, 

 sometimes causiiig 

 death and often a 

 curling or dwarfing of 

 the leaf and malfor- 

 mation of the plant. 

 They are seldom of 

 enough importance 

 to necessitate reme- 

 dial measures, but 

 when they attack 

 small plots of cotton 

 planted for purposes 

 of selection, etc., it is 

 advisable to spray 

 with 40 per cent nic- 

 otine sulphate used at the rate of three-fourths of a pound to 100 

 gallons of water. Preventive measures, such as fall and winter 

 plowing, to destroy them on their weed host plants, are nmch more 

 effective than direct remedies. 



[G. 5.— Cotton aphis: a, Winged female; ab, dark female, side \iew; 

 b, young nymph, or larva; c, last stage of nymph; d, w-ingless fe- 

 male. All much enlarged. (Chittenden.) 



Armadillidium vulgare Latr., PorceUh Ictetns Latr., etc. 



' A phis gosDt/pii Glov. 



