42 
all the Plusias, on account of the long abdominal space without legs, 
have to bend upward, or loop the central portion of the body in 
moving, and hence may be classed among the measuring or span- 
worms, so far as the method of progression is concerned. They eat 
large, irregular holes in the leaves of the cabbage, but do not appear 
to be confined to this plant. They spin their cocoons and pass the 
larvae state between the leaves, or in some sheltered place. The Eu¬ 
ropean species, P. gamma , to which it appears to be quite closely 
allied, occasionally appears in great numbers on the continent, doing 
incredible mischief to the market gardens, eating up the peas and 
beans, so that only the stalks and fragments of the leaves are left; 
whole fields of culinary plants have been consumed by them, and 
even crops of hemp. It is therefore possible that under favorable 
conditions our species may develope in such numbers as to he seri¬ 
ously injurious. 
Curtis, from whose work on Farm Insects these facts are obtained, 
remarks that: “These extraordinary swarms of insects, and their irre¬ 
gular returns, may be sometimes owing the mildness of the foregoing 
winter; in the instance just related there had been no severe frosts 
either in the winter or spring, so that the previous autumnal broods 
of caterpillars lived through the cold season, and it necessarily fol¬ 
lowed that an immense number of the moths were produced, and the 
spring and summer which succeeded proving favorable to their increase, 
they became more abundant than they had ever been known before.” 
We may remark here in passing, that this species,— P. gamma ,—is a 
widely dispersed insect, being found not only all over Europe, but 
also over a large part of Asia and even in North America. 
The Plusia moths, unlike most of the Noctuidae , flv about in the 
day time, in sunshine as well as in dull and even damp days. But 
they are exceedinglv shv and difficult to catch. 
The number of broods of this species in a season, is yet a matter 
of some uncertainty; that there are two, is evident from the fact, that 
the larvae reared by myself, and also those by Prof. French, were 
taken in August and appeared in the perfect state about the first of 
September. This brood usually remains in the pupa state about two 
weeks or a little less. The proper care in making our collections 
would probably have decided this point, but attention not having been 
called to it before, it was overlooked. But it is quite certain we have 
two if not three broods; that it is three brooded in the southern 
states, is rendered eertain by the fact that Mr. Grote records its 
capture in Alabama as early as February 20th. 
According to Stephens, there are three broods of P. gamma in 
England, the first appearing in April, the second in June, and the 
third in September. Curtis states, that in France it is most abundant 
in July and October. Duponchel, in his catalogue, says it is found 
“all the year.” From the same catalogue we learn that the moths of 
the European species, here named, make their appearance, or rather 
are found, as follows: 
Orichalcea. F. Switzerland. In July. 
Bractea. F. Alps. In August. 
Auriftra. H. Spain and France. In July. 
Testacea. L. Europe. In June and August. 
Ckalcites , Esp. Italy and France. June and August. 
