Just What Do Caterpillars Eat Anyway?
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.
Selective Eaters – To some, the answer to “what do caterpillars eat?” might be apple trees, cherry trees, or alder trees. Many of us have seen these types of trees covered with caterpillar nests in the spring, and it would seem that the butterflies have simply singled out the nearest tree for laying their eggs, not particularly caring what the tree is. A collection of caterpillar nests in an apple tree should give us a clue however. A particular species of butterfly selects only the apple tree as a place to lay its eggs. The apple tree becomes the host tree (or host plant) for the crop of caterpillars to come. The caterpillars, the young ones of that particular butterfly species, need apple tree leaves as their source of nourishment, and perhaps no other type of leaf will do.
People who raise butterflies as a hobby need to know what foods the immature butterflies (caterpillars) require, and often will make certain they have those plants or trees handy that will provide the caterpillars with the type of food that is essential to them. The Cabbage White butterfly, regarded as a pest in vegetable gardens, lays its eggs in cabbage and mustard plants, that being the vegetation the hatched caterpillars rely on for food. The Tiger Swallowtail won’t touch your cabbage plants, but will lay eggs on the vegetation of your black cherry tree should you have one.
We have a tendency of regarding all caterpillars as pests (and many can be) except of course the little fuzzy banded ones about the size of your little finger. Yet we enjoy nothing more that having a host of butterflies in our yard every summer. Thanks to a rather complete metamorphosis, the butterfly looks nothing like a flying caterpillar which in a sense it is. Butterflies, with the exception of some species that suck the juices from aphids, only drink nectar and don’t eat anything. The message then, is if we want to continue to enjoy caterpillars, it may pay to be selective about which kinds of caterpillars we want to get rid of. Of course if you’re going to choose between the caterpillars and your apple tree, the caterpillars are going to lose.
Most Caterpillars Are Beneficial – If you want to distinguish the good guys from the bad guys, the following sampling may get you started. If nothing else, you’ll discover that while some species of caterpillar are destructive and will eat your favorite plant, many others are quite beneficial, eating mostly what we consider to be weeds, and in one or two cases, feasting on aphids. The caterpillars that are offspring of the famous Monarch butterflies feast solely on the milkweed plant, Painted Lady caterpillars use thistles as their host plants, while several varieties zero in on nettles. The Red-Banded Hairstreak, perhaps not wanting to offend anyone, lays its eggs on fallen oak leaves, which provide the meal for its offspring.
Some Of The Bad Guys – A number of caterpillar species use grasses or clover as their host plants and sole source of food. While we may see a variety of butterflies in our flower garden, most of them are there in search of nectar, and lay their eggs elsewhere, where the hatched caterpillars will eventually feast. There are a few varieties that consider garden flowers as desirable host plants, such as the Pearl Crescent which prefers asters, several Fritillary species which use violets or violas as hosts, and the Buckeye, which may choose from a number of popular garden flowers. The Viceroy, a fairy common species of butterfly, is often the culprit as far as finding your apple, cherry or plum tree suddenly loaded with caterpillars. If not the Viceroy, the finger of blame may point to the Red Spotted Purple butterfly.
What do caterpillars eat? On the whole, the number of species of caterpillars apt to be found eating in your fruit trees, ornamentals, or vegetables is rather small, a definite minority, with the White Cabbage, Viceroy, and Buckeye probably accounting for the bulk of any damage you are may suffer. Recognize the caterpillars of these three species as far as any plans for extermination are concerned, and leave the rest of the little creepy crawlers alone.