Nature Bulletin No. 43   December 1, 1945
Forest Preserve District of Cook County
Clayton F. Smith, President
Roberts Mann, Superintendent of Conservation

****:PLANT AND ANIMAL IMMIGRANTS

When foreign plants and animals are brought to a new country they 
either become naturalized and thrive, or they cling to their old ways and 
die out. after they, too, find new freedoms because they leave their 
enemies, competitors, parasites, and some of their diseases behind them 
-- much as immigrant people do.

The United States now supports about 300 times as many people as it 
did when Columbus discovered America. This is possible because the 
domesticated plants and animals that the early settlers brought with 
them give much higher yields of food and clothing than the Indians got 
from wild ones,

But now some of these domestic animals and plants go wild. Honey 
bees leave their hives and do very well in hollow trees. The banks of 
many ponds created to hold and breed German carp broke in the 1880's 
and in a few years carp were the most common fish in the lakes and stre 
aras of such states as Illinois. Pigeons, starlings and sparrows in 
Chicago -- and in many other cities -- have become a nuisance. 
Abandoned dogs and cats have learned to hunt for themselves and rear 
their young in the forest preserves. The ringneck pheasant has increased 
in such numbers that in some states they are crop pests in spite of the 
fact that millions are killed annually by hunters.

Carelessly, man has also brought here many household pests -- such as 
mice, rats, sparrows, starlings, cockroaches and bedbugs; as well as 
crop pests such as the Hessian fly, the European cornborer, the 
Japanese beetle; and weeds like the European bindweed, the Russian 
thistle, the Canadian thistle.

Other stowaways -- including the nightcrawler and several other species 
of earthworms -- are actually beneficial.

They may be foreign in origin, and cause lots of disturbance and 
trouble, but after a long enough time they change their ways and find 
their place and become Americans just like the rest of us.