At first glance, the answer to “what do caterpillars eat?” might be (1) anything, (2) everything, or (3) my favorite plant. Caterpillars do not eat just anything; they are rather choosy in fact. Nor do they eat everything, though when you consider that different caterpillars have different tastes, a large number of different caterpillar species may dine on a large number of different plants. As to your favorite plant, that would depend upon the species of butterfly or caterpillar frequenting the area in which you live. Some caterpillars may be opportunistic eaters, but most of them have definite preferences, or in some cases, they will only eat from a specific species of plant.