40 BULLETIN 15 7, U. S. NATIONAL MUSEUM 



As would be expected, most of the local butterflies make their first 

 appearance in spring earlier than they do ,in Massachusetts. This 

 is particularly true of all the species that hibernate as adults or as 

 pupae, and of the larger species generally. But among the smaller 

 butterflies that hibernate as caterpillars there are some curious 

 exceptions. 



The most extraordinary of these exceptions is the silvered bog 

 fritillary {Brenthis myrina), which first appears in the vicinity of 

 the District a full month later than it does at Boston — and even at 

 Ottawa, much farther north — and nearly six weeks later than it does 

 at Albany. Furthermore, in this region it has only a single brood, 

 flying in midsummer, instead of three broods as about Boston. 



Though the hovering skipper {Poanes massasoit) does not appear 

 here until about the first of July, in New England it is on the wing 

 in the first half of June. Similarly, Leonard's skipper {Erynnu 

 leonardus) also appears in Massachusetts more than two weeks in 

 advance of its earliest appearance in the District. 



The goggle eye {Ceroyonis alope) is first seen, as casual individ- 

 uals, somewhat earlier here than about Boston, but the main emer- 

 gence takes place here about a week later than at Boston. 



The grass nymph {Satyrodes eurydic&) first appears in the District 

 a month earlier than in the vicinity of Boston, but its period of 

 maximum abundance is approximately the same in both places — 

 possibly slightly later here. 



The wood nymph {NeonymyKa eurytus) appears at precisely the 

 same time here and at Boston. 



The late appearance of many District butterflies and the long sea- 

 son of others, as of the satyrids, possibly are correlated with the curi- 

 ous and unusual irregularities in the temperature in spring, particu- 

 larly the occurrence of hot spells during which the caterpillars — or a 

 greater or lesser proportion of them — become lethargic and do not 

 feed. This conclusion is suggested by the curious fact that the two 

 widely distributed satj^rids {Neonymfha eurytus and Gercyonis 

 alope) always make their first appearance in low wet woods near 

 cold streams and are not seen until later in the warmer and drier 

 areas. 



Another fact pointing to the same conclusion is that several Dis- 

 trict butterflies appear earlier if the spring is cold than they do if 

 the spring is warm or marked by severe hot spells. This was strik- 

 ingly evident in the spring of 1930, as is shown by the observations 

 given in detail beyond. 



The habits of quite a number of the butterflies in the District differ 

 more or less from the habits of the same species farther north. Thus 

 in this area the two sexes of Poanes hoboinoh and of P. zabulon 

 inhabit quite different regions. The males are found in damp glades 



