RESEARCH ON CONTROLLING INSECTS WITHOUT 
CONVENTIONAL INSECTICIDES 
In the early days of agriculture, nature's ownchecks and balances were 
the only curbs on noxious insects. But as farming expanded and farmers 
aspired to a more efficient and dependable agriculture, and as new foreign 
insect pests inadvertently became established in the United States, insect 
control became increasingly necessary. 
Most of the estimated 700,000 described species of insects in the world 
are harmless. Some 10,000 species in the United States have been classed 
as public enemies, capable of causing trouble for man under certain condi- 
tions. Entomologists consider that several hundred of these species are 
particularly destructive and generally require some measure of control in 
order that we may feed and clothe the nation economically and conserve its 
agricultural manpower and resources. One hundred and twenty-three of 
these noxious species are immigrants, many of which are among our most 
destructive insects, 
Men and women were concerned with insects in this country over 200 
years ago. Insect pest problems arose before the nation was born. As the 
population grew agricultural production also increased and some of our 
insects thrived under conditions ideal for their survival. From time to time 
new crops were introduced from abroad, some of which proved to be attrac- 
tive to our native insects. Of even more significance, world commerce 
brought many new pest species to our shores, unaccompanied by their 
natural enemies. Some of the arrivals were not pests in their native lands 
but rapidly acquired this status under conditions in the United States. 
The growth of commerce called for better agricultural commodities for 
shipment and storage. Consumers also demanded better quality products 
and discriminated against those stunted or damaged by insects. This forced 
farmers to use more effective measures against insect pests. 
Improved tillage and crop rotation helped control some insects and cut 
down on insect damage to farm commodities. Special cultural practices 
and the observance of safe planting dates (a practical aid in control of the 
hessian fly) have been of value in the protection of certain crops from 
injurious insects. 
The development and use of insecticides is a significant chapter in the 
history of our expanding agriculture. Insect control was at first a secondary 
use for some industrial chemicals such as paris green and london purple, 
but for the past half century chemicals have been developed specifically for 
insect control. During the 1940's, DDT, developed to protect our armed 
forces from insect pests, proved useful in agriculture. More recently, some 
highly successful broad-spectrum organic insecticides were also developed 
and greatly improved the efficiency of our agriculture. 
However, great interest both historically and currently lies in other 
directions. For example, nature's own control agents, the parasitic and 
predatory insects and insect diseases, have received and continue to receive 
much research attention. 
