CHAPTER V. 



INFLUENCE OF WEATHEK. 



It seems curious that observers should be so divided in opinion as they 

 are concerning so simple a point as whether a mild or a severe winter 

 is the more apt to be followed by a bad worm season. Of the corre- 

 spondents of the department, some hold one view, others the directly 

 opposite opinion, while still others state that the degree of severity of 

 the winter makes no difference whatever with the extent of the ravages 

 the succeeding season. Those holding the last view base their opinion 

 on the fact that they have actually known disastrous worm seasons to 

 follow cold and warm winters indiscriminately.* 



Those holding the opposing views referred to also claim to found their 

 opinions upon actual experience. The advocates of the view that a 

 severe winter will be followed by the worm give as their explanation the 

 fact that during warm winters the moths come forth from their hibernat- 

 ing quarters and die of hunger, whereas while in winter quarters and in 

 the true state of hibernating somnolency not only is no food necessary, 

 but they are less exposed to dangers of all kinds which would assail 

 them if they flew out, attracted by sunshiny weather. The upholders 

 of the theory that warm winters are more apt to be followed by the worm 

 simply urge the idea that the severity of the colder winters kills the 

 hibernating individuals. 



The truth of the matter, as it seems to us, is that, other things being 

 equal, a warm winter is more favorable to hibernation than a cold one. 

 It seems to be true that the cotton-moth was originally a tropical or sub- 

 tropical insect, and that only in favored localities within the limits of the 

 United States can it hibernate at all. As we go northward the winters 

 become too severe for survival from one season to another. Farther 

 south, then, winters approaching to this northern severity must be un- 

 favorable, while winters approaching those of the normal habitat of the 

 moth will prove favorable. This is reasoning in the abstract. Actual 

 experience seems to show that occasionally the greatest worm years 

 foHow undoubtedly cold winters. This seems to have been the case with 

 the season of 1873, in some parts of Alabama at least. Such instances 

 we think, however, must be laid to a combination of other causes, work- 

 ing through a series of years; and that, instead of the severity of the pre- 

 ceding winter having been the sole cause, the ravages of the worms 

 would have been even worse had a mild winter come before. 



Another and mor"e important point concerning the influence of weather, 

 brought out by the 1878 circular, was, do the worms flourish most in a 



* This fact has been used as an argument for the migration theory. 



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