INSECT PESTS 43 



some of the insects being crushed in contact with the 

 fibre during the process of ginning. If, however, 

 before the cotton is ginned, it is spread out and 

 exposed to the sunshine the insects take to flight and 

 the staining is thus obviated. 



Locusts. These insects sometimes cause consider- 

 able damage by devouring the leaves and young 

 plants and thus rendering replanting necessary. 

 Paris green has been found to be useful in destroying 

 these insects, but the most effective plan is to place 

 upon the ground little heaps of bran mixed with 

 molasses and arsenic. 



Leaf -blister mite. The leaf-blister mite (Eriophyes 

 gossypii), although not an insect, is included here for 

 convenience. It is so small as to be invisible to the 

 naked eye, but its attack can be recognised by the 

 leaves becoming curled up and blistered. The blisters 

 or galls are at first of the same colour as the leaf, but 

 later become reddish brown. The mites inhabit 

 these galls and lay their eggs in them. The galls do 

 not appear upon the leaves only but on all parts of 

 the plant except the root. The mite does not usually 

 do much harm to full-grown plants, but sometimes 

 causes serious damage to young plants, thereby 

 diminishing the crop. In order to check this pest 

 the infested leaves should be gathered and burned. 

 The application of sulphur or a mixture of sulphur 

 and lime has also been recommended. 



Disinfection of Cotton Seed. When cotton seed is 

 transported from one locality to another, there is 

 always the danger of diseases or pests being carried 

 in it and thus being introduced into new regions. 

 It is therefore desirable that some method of fumiga- 

 tion or disinfection should be practised in order to 

 avoid the introduction of pests which, if once estab- 

 lished, may cause enormous damage and, as a rule, 

 can never be completely exterminated. Disinfection 

 is at present effected chiefly by the following methods, 

 viz. (i) fumigation with hydrogen cyanide, (2) 

 fumigation with carbon disulphide, and (3) treatment 

 with solution of mercuric chloride (corrosive sub- 

 limate). 



