VARIATIONS IN HABIT AND IN LIFE. 1417 



that a certain percentage, in some plural brooded butterflies advancing 

 with the season, do not give out the butterfly when they are expected to, 

 but keep the inmate prisoner over to another year, as though winter were 

 already at hand ; while their sisters emerge and leave progeny to take their 

 place. 



Variation in habit of another kind has been observed in the hibernation 

 of the Pacific coast Melitaeid, Lemonias chalcedon, the habit varying 

 with the altitude at which the creature lives ; if it be high up in the moun- 

 tains, the caterpillar hibernates in special webs of considerable toughness, 

 like our Euphydryas phaeton ; if, on the contrary, on the sun-baked 

 plains, the caterpillars leave the webs common to their early life and crawl 

 into the ground to hibernate. 



These irregularities give a piquancy to the studies of the life histories of 

 butterflies, for the unexpected is often happening, and even members of 

 the same brood do not behave alike, but show an individuality which is 

 surprising. It may thus happen that two observers following the life his- 

 tory of the same insect may reach very diflferent conclusions. For as the 

 season, and especially winter and its adjuncts, sudden and considerable 

 changes of temperature, have much or primarily all to do with all this 

 complexity of life, so observers at different latitudes may need to com- 

 plement each other's observations to learn the whole behavior of an in- 

 sect ; and comparative observations north and south are highly desirable 

 wherever any such question arises. Nothing surprised me more than to find 

 that most of the Pamphilidi, which I had found very commonly single 

 brooded at the north, were double or even triple brooded at the south. With 

 us they are such slow feeders that I naturally assumed that such were their 

 habits everywhere ; but the observations of Chapman, Abbot and others 

 prove quite the contrary. 



A verj' considerable number of digoneutic butterflies show some varia- 

 tion in the numbers of the different broods, uniformly, year after year. 

 In all such cases something disturbs the regularity of habit or uniformity 

 of life ; the lives of some are prolonged, of others hastened at special 

 stages, and these are the butterflies whose life histories require the most 

 careful and searching observations, continued and repeated, and the study of 

 which is fullest of interest and significance. 



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