Pe eos Db ONe BU Ti eet. N 1} 
Clean cultivation, with elimination of hedgerows and roadside brush, also 
simplifies the ecosystem. (Courtesy of Illinois Natural History Survey). 
There is a real fear abroad that chemical controls not only carry un- 
known hazards, result in insect resistance, pollute water and air, and seriously 
damage wildlife, but that they are actually self-defeating. Dr. Cole writes 
about New York apple growers who spray up to twelve times a year but are 
ever on the alert for new pests. Because the spring is damp, they must have 
sod under the trees to support the heavy spraying equipment. Mice, which 
girdle apple trees, also love to nest in the sod. So rodenticides must be applied 
in addition to the massive doses of insecticides. 
What next? Says Dr. Cole: ‘‘When we accept the proposition that natural 
selection will fill vacant ecological niches, we must logically begin to wonder 
whether total eradication of destructive forms is desirable.’’(2) Non-selective 
pesticides may result in other empty niches than that of the target species, 
leaving niches open for possible undesirable species. Biotic communities are 
hike our bodies. When anti-biotics have emptied the niche of harmless in- 
testinal flora in our bodies, in addition to the disease-producing bacteria which 
were our target, harmful staphylococci, resistant to the drug, are liable to 
fill the niche left by the harmless flora. An example of this occurrence in a 
forest community is the rise to pest status of the spider mite after treatment 
for spruce budworm. 
In nature, organic material tends to be used. If only a few species can 
adapt to an environment, many individuals from those species will appear, 
to feast as long as there is food and safety, using up the organic material. 
In agriculture, the many individuals of a few species are the pests, and the 
farmer inadvertently encourages this situation by making his field uninhabit- 
