A. Introduction

The protection of farm crops from destructive insects is one of the most important requirements for successful farming. From the time the seeds are planted, throughout the period of the growth of the plants, and even after the crop is harvested, insects cause an economic loss. Different crops vary in their susceptibility to insect damage but none entirely escape attack Insect damage may result in total crop loss This loss may even exceed that loss indicated by poor stands, unthrifty growth, reduced yields, or poor quality

Such insects as the grasshopper, or "locusts" as they are called in the eastern hemisphere, boll weevils, corn borers, etc., are quite familiar to a lot of people because of the spectacular damage they cause. In addition to this type of insect outbreak, there is the continual drain on practically all crops caused by lesser and more obscure forms of insects whose work may be unnoticed, such as root infesting insects and sap sucking species.

The larger, more conspicuous insects such as armyworms, cutworms, and beetles, as well as signs of their work, are quite familiar to most people. The injury caused by the minute forms are often mistaken for such things as poor seed, unfavorable soil conditions, or plant diseases. It is now known that many serious plant diseases are carried and spread by insects.

Agriculture in general favors the multiplication of insect pests because many farm crops are not native to the area in which they are grown and have not developed an immunity to the particular pest. Another important reason for the growing seriousness of the insect problem is the introduction of injurious species from abroad. The increased volume of commerce from abroad and the speed of airplane travel has greatly increased the possibility of accidental introduction of insects.

Man's survival depends, to a certain extent, on some insects. Insects produce honey, silk, shellac, various dyes and drugs, and are responsible for the direct production of much of our food products. There would be little tree-fruit without the aid of insect pollinators. Over fifty varieties of vegetables are dependent upon insect pollination. Most of our fresh water fish would disappear if insects were to vanish. The majority of insects are beneficial to the farmer.

Successful insect control depends first of all upon a knowledge and understanding of the insects themselves. Each insect species or closely related group has its own characteristics and habits. These characteristics and habits have a great deal to do with the success encountered in controlling them.