It will be seen that the average number of boll worms per 100 

 bolls between July 12 and August 30 was reduced by the two campaigns 

 from 74 in 1917 to 11 in 1919, a striking testimony to the value of a 

 boll-picking campaign when efficiently carried out. If the first two 

 weeks of September are included for the calculation of the average 

 the improvement is not so obvious as owing to the exceedingly rapid 

 rate of multiplication of the pink boll worm, the number of worms 

 present at the end of all three seasons approximated to the maximum 

 population which can be supported by the cotton plants. 



In order to arrive at the ratio of the damage done in the different 

 years it is necessary to go one step further in our calculations since 

 the damage done is proportional not to the number of worms per 100 

 bolls but to the number of worms per fedddn or per 100 plants. In 

 Table IV (a) are given the numbers of green bolls per 100 trees at 

 various dates from August 2 to September 13 which for the purposes 

 of our present calculation may be taken as the useful boiling period. 

 These figures are the average of seven sets of observations. From 

 them together with the numbers of boll worms per 100 green bolls 

 (given in Table III) we can calculate the number of boll worms in 

 the green bolls on 100 plants as given in Table IV (b). 



TABLE IV. 



From the above table it will be seen that the average number of 

 worms per 100 plants was reduced in 1919 to less than one third of 

 the number in 1917. The damage done to the crop will be proportional 

 to the number of worms present. In 1917 Mr. Ballou calculated that 

 1 7 per cent of the crop was lost as a result of the pink boll worm attack. 

 Therefore if we accept his figure, 614/1993 (see Table IV) of 17 per cent 

 of the crop was lost in 1919, i.e. 5-2 per cent. In other words the saving 

 amounted to 11-8 per cent of the crop, or, if we estimate the crop 

 as 3-5 qantdrs per fedddn, to 0-41 of a qantdr per fedddn, or, if we value 

 the qantdr. at L.E. 20, to L.E. 8-200 milliemes per fedddn. The two 



