During the 1960's, the tobacco budworm, the caterpillar of a night flying moth, became one of the most serious pests that cotton growers have ever had to face.
These caterpillars would eat the bolls, flower buds, and flowers of the cotton plant. In the process, they would cause millions of dollars worth of damage every year.
Growers promptly turned to organophosphate insecticides that penetrated the skin of the caterpillar and acted as a nerve poison. At first, this treatment seemed to be working, and one formulation of the insecticide killed about 60% of the budworms.
But 40% survived!
Fighting back, the growers turned to a different insecticide formulation that killed 70% of the budworms, but still some survived.
In the lower Rio Grande Valley, farmers applied different mixtures of organophosphates up to 25 times, and still the crop could not be harvested. The insecticide treatments did, however, kill all the spiders that normally ate the budworms.
Resistant budworms always survived, being more fit and better adapted to a now predator-free environment, no matter how laden it was with chemical poisons.
Incredible environmental pressure, exerted by the farmers and their poisons, ensured that within a few years there were millions of resistant budworms and no spiders. By 1969 the budworms had won, and 40 cotton gins were closed forever. Evolution had taken only 8 years and left economic disaster behind it.