Nature Bulletin No. 687   Septe4mber 29, 1962
Forest Preserve District of Cook County 
Seymour Simon, President
David H. Thompson, Senior Naturalist

****:PESTICIDES

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.

Beginning 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 
insecticides .

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 
our food.

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.