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

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.

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