1416 THE BUTTERFLIES OF NEW ENGLAND. 



kinds — iind they are pretty numerous — which act as if they had never 

 heard of winter ; this is particuhirly the case with polygoneutic but- 

 terflies ; for it is a couunon tiling in [ilural hrooded Ijuttcrflies to find 

 every possible stage on the ground as winter conies on ; tlie more the 

 number of l)roods is nuiltii)lied, the more confused do tlie distinctions 

 between them become ; and in many cases, were the season longer, no 

 doubt it would become quite impossible to trace them. The butterflies go on 

 sucking honey and laying eggs, the eggs hatching, the caterpillars eating, 

 until a heavy frost kills ofl' all the unprepared and terminates the history 

 of the species for the season ; those of one stage survive the shock, the 

 others die ; this is the case with several of our swallow-tails and yellow 

 butterflies and with not a few others ; sometimes it is the caterpillar, 

 sometimes the chi-ysalis, at others the butterfly which survives; the egg, 

 in such cases, never. 



To leap at once to the most striking case known to our fauna of a differ- 

 ence in habit according to the season, we would point to Basilarchia 

 archipi)us, the caterpillar of the latest l)rood of wliich constructs from its 

 food plant with utmost care a hibernaculum in which to pass the winter, 

 beginning to do this long before any of the leaves of the plant show a ten- 

 dency to fall, and securing the one chosen so firmly to its twig that it re- 

 mains attached the winter througli ; yet with this common butterfly no 

 instance has been given where a caterpillar of an earlier brood showed the 

 remotest tendency toward such action ; where two brooded, it is only alter- 

 nate generations that follow tliis instinct, warned thereto perhaps by the 

 growing desiccation of the food or the chill of the nights. 



Winter of course intervenes to alter the mere duration of certain stages 

 in alternate generations, as in the case of double brooded butterflies which 

 winter as caterpillars ; the wintering caterpillar suffers a torpidity of which 

 the summer caterpillar knows nothing ; but just here, in very curious con- 

 trast to the case of Basilarchia, we have the instances related in the text 

 where in certain Argyunidi, and probably also in some jNIelitaeidi, at the 

 very stage of caterpillar life when in the autumn the creatures go into 

 hibernation, the caterpillars of the summer become lethargic, sometimes 

 remaining in this stage till lethargy merges into the dormancy of winter, 

 sometimes awaking after a time and pursuing again the even tenor of their 

 way. 



Although it seems absurd to speak of a lethargic chrysaUs, yet phenom- 

 ena of precisely similar nature to this summer dormancy of the larva, and 

 producing exactly the same result as far as the outcome of the annual his- 

 tory of the sjiecies is concerned, take place with some chrysalids. Thus 

 the diff"erence which is so common in digoneutic butterflies which winter as 

 chrysalids, wliere the summer chrysalis is short lived and the winter long- 

 lived, has the uniformity whicli this implies interfered witii when we find 



