Timed Planting Insects usually appear at about the same time every year, and you can time your plantings to avoid the heaviest feeding stages. Of course, variations in weather will affect emergence, so keep your own records from year to year, and check with your neighbors and local growers. Or you can plant after the insects have gone, and then cover your crop to extend the growing season into the fall. Some plants have a natural resistance to particular insects, and you can take advantage of these traits by selecting resistant varieties. Nonpreference plants either turn an insect off or simply lack an attractant to turn on the insect.
Some plants actually contain substances that injure or kill pests.
This is another type of resistance, called antibiosis. Marigolds and garlic are commonly used to repel certain insects because of their antibiotic qualities. Tolerant plants simply can withstand insect damage. Some have the ability to quickly regenerate plant tissue so they can suffer a loss of up to 30 percent of their leaf mass without much decrease in yield. Other plants are tolerant because of their tough tissue.