10 



have also diminished considerably during 'the period under review. 

 Apart from the boll worm campaigns there are several factors which 

 may have affected the relative abundance of the pink boll worm, 

 namely, parasites, the weather, and changes in agricultural practice. 



To deal with these in order, the very extensive breeding records 

 of the Entomological Section give one no reason for thinking that 

 there has been any substantial increase during the period under 

 review in the parasitization of the pink boll worm at any given date. 

 A number of different parasites were abundant in 1916 and even before, 

 but have always been limited in their utility by the fact that they 

 are unable to get at the worms until the bolls have opened. 



The weather, also, is very unlikely to have had any very great 

 effect on the pink boll worm. In the first place the weather during 

 its breeding season, i.e. from June to October, does not vary very 

 much on the average from year to year, and in any case the worm 

 lives snugly tucked away inside the boll and is much less susceptible 

 to changes in the weather than are external feeders. The case of 

 the pink boll worm cannot be compared with that of the cotton worm 

 for instance. In the case of the latter, favourable weather during 

 October and November may give the autumn generation on the bersim 

 exceptional opportunities for multiplying and lead to an exceptionally 

 severe attack on the cotton during the following summer. 



It seems probable, then, that it is to changes in agricultural 

 practice that one must look for the causes of the decrease of the 

 boll worm, and in Lower Egypt the only substantial change in this 

 respect has been in earliness in pulling up the cotton plants at the 

 end of the season. 



The experiments of Mr. Cartwright (late Inspector of Gharbiya, 

 now Director of the Higher School of Agriculture, Giza), who showed 

 that by reducing the watering after the middle of July he could get 

 practically the whole of the bolls to ripen at a very early date, marked 

 a great advance in the question of pink boll worm control. Partly 

 as a result of these experiments, partly as a result of the direct observa- 

 tion of the same fact by others, partly as a result of the more general 

 realization that it is no use keeping cotton standing after a certain 

 date, as all late bolls are spoilt by the worm, and partly owing to 

 the fact that Inspectors have not insisted on the bolls being picked 

 before the sticks are pulled, the average date of the pulling of the 

 sticks has become earlier and earlier during the past few years. 



To illustrate this, one may mention that in Qalyubiya in 1916 the 

 pulling of cotton sticks did not become at all general till towards 

 the end of October, about two-thirds of the total were pulled by 

 November 20, and quite considerable quantities remained standing 

 right through December. In 1919, on the other hand, there were 



