The Colorado Potato-Beetle. 
371 
into America at Quebec about the year 1856-7, probably, it is 
said, in the egg state on refuse cabbage-leaves, has increased and 
spread over all the Northern States; and from the habit possessed 
by its caterpillar of burying itself in the heart-leaves of the 
growing cabbage, and devouring them, has become a great 
nuisance. It is estimated to destroy annually around Quebec 
240,000 dollars' worth of this vegetable. The wheat-midge or 
Hessian fly {^Cecidomijia destructor), the codling-moth or apple- 
worm (^Carpocapsa ponionella), the gooseberry sawfly, the bee-moth 
or wax-worm (^Galleria cereana), besides many parasites of 
domestic animals, all well-known European insects, are so many 
other instances. But the case which more nearly concerns us is 
that of the Asparagus beetle (^Crioceris asj)aragi), from the fact 
of its belonging to the same tribe as the Colorado potato-beetle, 
and having: similar habits. This well-known Ensrlish insecr 
was introduced into America at Long Island no longer ago 
than in 1860, and has already proved so destructive that, in 
one year, in the State of New York alone, the loss to gardeners 
from the damage done to asparagus-beds was estimated at 
50,000 dollars. The Galeruca calmariensis, which devours the 
foliage of the elm, is another beetle of the same tribe accli- 
matized in North America from Europe. It may fairly be 
urged, if these characteristic European species have become 
acclimatized and destructive in North America, what valid 
ground is there for supposing that the potato-beetle, so nearly 
allied to them in organization, will be unable to establish 
itself in Europe. 
In answer to this, it may be stated, in the first place, that the 
establishment of European species in other distant countries, as 
all botanists and zoologists well know, is not reciprocated to the 
same extent by the acclimatization of foreign species with us. 
Many of our commonest plants and insects have followed our 
colonists even to the antipodes ; and in New Zealand, especially, 
they threaten to crowd the native species out of existence ; but 
no antipodean natives have made the reverse migration. This 
curious fact has been accounted for by supposing that European 
organisms of the lower types have, like the European man, 
become so invigorated by repeated readjustments to the greater 
geological and climatal changes of past ages, which our continent 
lias witnessed, that they have become more encroaching and 
more successful under new circumstances than the natives of 
most other regions. It is difficult to see how this argument can 
apply in comparing the biological conditions of North America 
and Europe ; but the fact nevertheless remains that, so far. North 
American species have not sent colonies to Europe in anything 
like the same proportion as European species have with regard 
