T aan EG? gl au rE ee Pah ait ie eee 
Pres eau § 
- North Cape to the Mediterranean ; our congeneric A. Milberti is 
Sy found south of the northernmost parts of the United 
1876.) A Cosmopolitan Butterfly. II. Its History. 603 
undergo their final transformations in the latter half of August 
and early in September, the autumn brood of butterflies first ap- 
pearing late in August and continuing on the wing until the end 
of October, when they hibernate. 
This account does not correspond with the history of the same 
insect in Europe. Meyer-Diir states that in Switzerland the 
butterfly may be seen on the wing from April to the end of June 
(wintered specimens), and from the middle of August until late 
in October ; that is, it is single-brooded. Many authors speak of 
it as double-brooded, without mentioning the specific times at 
which it may be found ; while others give the same seasons as 
Meyer-Diir and call it double-brooded, mistaking the double ap- 
parition of the same brood (winter intervening) for distinet 
broods. My own observations in the neighborhood of Geneva 
and Paris lead also to the conclusion that the insect is single- 
brooded ; and no entomologist, to my recollection, has given the 
best proof of digoneutism, namely, two distinctly separated dates 
for the apparition of the caterpillar. Nevertheless, from the time 
of Ochsenheimer, who repeatedly says, “ Ich habe zwei Genera- 
tionen bemerkt,” different authors have claimed for this insect a 
double brood ; and until direct observation shall have determined 
the point, it should be considered, at least for some parts of Eu- 
Tope, an open question. In Switzerland and in England all ob- 
Servers seem to agree that it is single-brooded ; and this is in 
direct contrast to the digoneutism of the same insect in New 
; If this were a solitary fact, it would possess comparatively 
little interest, But if we compare the annual histories of the 
dozen or two butterflies either actually occurring both in Europe 
and in Eastern North America, or represented on either continent 
by intimately allied forms, —if we compare their histories, we 
find several other species which present similar peculiarities, 
and be led to believe that the case of V. cardui is only one illus- 
tration of a somewhat general law. ; 
-The European Aglais urticæ, for example, 18 generally double- 
. 
brooded ; occasionally a triple brood is mentioned ; it is one of 
the commonest of European butterflies, and reaches from the 
tates, and yet is triple-brooded in all parts of Canada. Everes 
2 Sane again, occurs throughout Europe, with the exception 
_ “certain northern and northwestern portions, and is double- 
