Nature Bulletin No. 687 Septe4mber 29, 1962
Forest Preserve District of Cook County
Seymour Simon, President
David H. Thompson, Senior Naturalist
The use of chemicals for the control of insect pests, rats and mice,
weeds, and the fungous diseases of cultivated plants has become an
increasingly widespread practice over the past century.
in 1867, Paris green -- the first successful insecticide -- was
used to control the Colorado potato beetle. During the next 75 years
other compounds of arsenic were used more and more for the protection
of such crops as fruit, vegetables and cotton. These were supplemented
by certain plant products -- pyrethrum from a chrysanthemum flower,
nicotine from tobacco, and rotenone from a few tropical legumes .
At the height of World War II, after a frantic search, it was found that
an obscure synthetic chemical, now nicknamed DDT, was a remarkably
powerful, long-lasting insecticide. In the Pacific and other theaters of
the war it was used on a large scale to control those insect-borne
diseases that have often decided the outcome of wars. It was a top-
secret weapon in the Allies' arsenal.
In 1945, DDT was released for agricultural, household and general use.
Large numbers of other synthetic insecticides followed in quick
succession. One group, the chlorinated hydrocarbons, is chemically
similar to DDT. Another main group is known as the organic
phosphates. Both proved so effective on insect pests that many older
poisons rapidly declined in popularity.
Soon it was discovered that these miracle chemicals were not unmixed
blessings. For example, it was found that DDT does not readily break
down, evaporate, wear off or wash off. While this is desirable for some
uses, there is the disadvantage that it accumulates in the body fat of
animals. It also shows up in milk and milk products. As a result,
research programs continually study these pesticides to determine how
and which ones may be used best.
At first, DDT worked like magic on houseflies. Sprayed lightly on the
walls and screens of homes and farm buildings, or added to paint, it
promised freedom from this age-old pest. After a few years, however,
flies no longer were affected by the poison and began to increase in
numbers. The few survivors had bred a race which is able to resist
extremely heavy dosages of DDT. Mosquitoes, roaches, lice, fleas and
many other pests are becoming resistant to the commonly used
Some pesticides set off a chain reaction. Elm trees in cities and towns
are often sprayed heavily with DDT to kill the bark beetles that spread
the Dutch elm disease. If this is done in summer, the poison clings to
the leaves until they fall in autumn. Later, as earthworms feed on these
decaying leaves, the DDT accumulates in their bodies. These worms,
though not killed themselves, can be deadly to the robins that eat them
the following spring.
Wildlife may suffer severely when wide areas are blanketed with heavy
dosages of insecticides in attempts to eradicate or control certain
invading insect pests. In extreme cases most of the birds, mammals, fish
and beneficial insects have been temporarily wiped out. In a few of
these instances, the misuse of insecticides has brought discredit on all
pesticides. In spite of these blunders in special cases, the wise use of
pesticides plays an important part in the production and protection of
In prairies, woodlands, wetlands, stream and lakes the story is entirely
different. The less these are disturbed the better. In our ever-growing
need for lands offering outdoor recreation, education and enjoyment to
the public -- these have their greatest value when allowed to remain as
nearly natural as possible.
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Update: June 2012