480 PROCEEDINGS OF THE THIHD ENTOMOLOGICAL MEETING 



are comparable inter se in other ways. The " dead " bolls were killed 

 before maturing (by the Pink Bollworm) the early green bolls were 

 killed before maturity (by picking) or ripened prematurely. Their 

 curves, as has been stated, are very similar, and are composed entirely 

 of " long-cycle " moths. (Plate 85.) 



The late green bolls are at first sight very puzzUng. Sixty-five 

 per cent, of the emergences from this lot were in April and May, followed 

 by none at all in June. The remaining emergences were observed in 

 July, August, October and November. 



This very great rush of emerging moths in April and May 

 is characteristic of the late green bolls only. The " open " bolls have 

 no parallel to show. In their case the emergence curve is a continuous 

 one over the whole period, a little steeper in the case of moths bred 

 from early collected material than from that collected later. 



There is only one explanation possible by which the late " green " 

 boll curve can be understood, and that is that the rush of moths emerging 

 in April and May did not belong to the long-cycle generation at all. 

 It seems much more probable that they belong to the winter genera- 

 tion, which I mentioned earlier. All that we know of this winter gene- 

 ration has been found out by the statistical method. In 1916 I drew 

 attention to the fact that in bolls collected in the field in the first three 

 months of the year there were varying numbers of Gelechia larvse of 

 small and medium size. The number of small and medium larvae found 

 in January was approximately in agreement with the number of medium- 

 sized ones found in February, whilst in March small and medium larvse 

 were almost absent. Nothing further was known of this winter-gene- 

 ration until these breeding results came forward. It was considered 

 not possible to verify the existence of the winter generation by direct 

 breeding methods, owing to the intolerance of Pink Bollworms to inter- 

 ference. 



It may now be assumed as nearly certain, that the winter-genera- 

 tion is produced by eggs laid before the end of November on the late 

 green bolls, that, owing to cold conditions, these eggs and the resultant 

 larvae mature very slowly — for which many parallels could be brought — 

 and that the winter-generation mainly belongs to the short-cycle. 



As to the relative economic value of worms harbouring in green 

 bolls, open bolls and dry bolls, it may be stated that very probably the 

 dead bolls are the least and the open bolls the most dangerous. 

 However, the worms in the open bolls will all find their way to the 

 giiineries, where a warm reception is provided for them in the seed- 

 treating machines. Of the bolls remaining in the field the green ones 

 are by far the most important, as they harbour more worms per unit 



