Sept. 1896.] Skinner: Study of N. American Butterflies. 109 
agos, while dry semi-withered food produces dark imagos of small size. 
Heat accelerates the pupal stage and cold retards it and the effect is 
shown in the imagos. The character of the season influences the re¬ 
sulting imagos and also the number of broods. Sometimes species 
which are usually single brooded may in special season become double 
brooded, and those which are normally double brooded may produce 
an additional brood. The individuals of these different broods differ 
and in some cases to such an extent as to have been described as differ¬ 
ent species. Nearly, if not all, butterflies produced from wintering 
chrysalids are different in appearance from the subsequent summer 
brood or broods. Pieris napi and rapce are whiter with the blackish 
markings nearly obsolete. Papilio turnns from wintering chrysalids in 
this locality look like the Arctic form. Species of Lyccena in their 
spring dress are very different from those produced later. Even what 
might be called anatomical differences are produced by season; thus in 
some of the Lycasnidae the spring brood is tailless, whilst the summer 
generation of the same insect is provided with these appendages. 
In passing from the sub-tropical heat of the Rhone Valley through 
successive zones which are to be met with before reaching the perennial 
snows of the Gorner Grat and the peaks overhanging the Riffel, a col¬ 
lection of insects may be made which represents in temperature a dif¬ 
ference of latitude as great as from Italy to Scandinavia. I am quite 
positive that if studies were made from large amounts of material from 
different localities the observing student would soon learn to tell from 
whence a given specimen of a species came, from its appearance alone. 
This is specially true of forms having a wide geographical range. 
In Anthocharis belia by prolongation of the pupal stage we get var. 
ausotiia which has the underwings (underside) white with yellowish 
green blotches, instead of being green with silvery spots. The spring 
brood of Vanessa antiopa has whitish wing borders instead of buff. In 
Holland a pale yellow border, and in Sweden, Norway and Lapland 
have white borders throughout the year. The same species from Penn¬ 
sylvania can be distinguished from California examples, the latter being 
more nearly related to the European form. Lyc<z?ia agestis, a well 
known little brown butterfly, with a marginal row of rich orange spots, 
common in the south of England during May and August, when pro¬ 
ducing but a single annual brood, appears in July as a variety {artaxer- 
xes ) that presents the black spots on the wings replaced by white ones, 
and which was for a long time on that account regarded as a distinct 
species. 
