COTTON 231 



are so isolated from those of other countries that counter- 

 balancing influences can only be artificially introduced, 

 and climatic conditions are almost invariable, insect pests 

 thrive to the greatest extent after once becoming estab- 

 lished, and, in some cases by reason by their recurring 

 attacks, have become quasi-permanent. In practice, 

 therefore, we find that such a pest as the Earias boll 

 worm, for instance, exercises a continuous influence on 

 the quality of the later pickings of cotton, the severity 

 of which varies each year, chiefly in accordance with the 

 time of maturity of the crop. This same pest contributes 

 more than any other to the loss in yield as well as in 

 quality in the manner mentioned, and it frequently 

 happens that in a late maturing year the estimation of 

 the cotton crop is rendered difficult at the time of ripen- 

 ing by the occurrence of a few days of cool or misty 

 weather which favours the activity of the pest. 



Efforts to suppress the virulence of the Earias boll 

 worm pest have been severely handicapped by the diffi- 

 culties in the way of carrying out the administrative 

 measures recommended. In order that the insects may 

 be reduced to their minimum in quantity during the 

 winter, it becomes necessary that all old bolls remaining 

 on the dead cotton sticks should be destroyed by fire, 

 as it is within these bolls that the Earias boll worm, as 

 well as the Gelechia seed worm, undergo their period 

 of hibernation to a great extent. The destruction of the 

 food plants of the species, such as volunteer cotton, and 

 the several species of Hibiscus growing in the country, 

 in conjunction with the dried bolls themselves, is a 

 necessity. The removal of the dried bolls from the dead 

 cotton plants is a rather laborious process., and, as the 

 dried plants themselves are the main source of fuel used 

 in the country, the insistence on the destruction of these 

 altogether is scarcely to be considered. Experiments have 

 recently been made with the conversion of the dried cotton 

 plants into charcoal, and this has met with some measure 

 of success. Our experiments show that, although the 

 weight of the fuel is decreased in the operation to about 

 25 per cent., the .calorific value of the charcoal is about 

 two and a half times that of the wood, so that the loss 



