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Long before the age of man, insects, inhabited the earth a group of extraordinaily varied and adaptable beings. Over the course of time a small percentage of the more than half a million species of insects have come into conflict with human welfare in two principal ways: as competitors for the food supply and as carriers of human disease. Disease-carrying insects become important where human beings are crowded together, especially under conditions where sanitation is poor, as in time of natural disaster or war or in situations of extreme poverty and deprivation. The control of some sort becomes necessary. It is a sobering fact, however, that the method of massive chemical control has had only limited success, and also threatens to worsen the very conditions it is inttended to curb. Under primitive agricultural conditions the farmer had few insect problems. These arose with the intensification of agriculture the devotion of immense acreages to a single crop. Such a system set the stage for explosive increases in specific insect populations. Single-crop farming does not take advantage of the principles by which nature works; it is agriculture as an engineer might conceive it to be. 2003 Nature has introduced great variety in to the landscape, but man has displayed a passion for simplifying it. Thus we undo the built-in checks and balances by which nature holds the species within bounds. One important natural check is a limit on the amount of suitable habitat for each species Obviously then, an insect that lives on wheat can build up its popultion to much higher levels on a farm devoted to wheat than on one in which wheat is intermingled with other crops to which the insect is not adapted.