Butterflies and Moths — Butterflies and moths can be difficult to find, but looking for known food plants makes the task easier. Different swallowtail caterpillars eat parsley, dill, citrus leaves and sometimes carrot greens. If milkweed grows in your area, monarch caterpillars will be on the plants in the spring or summer. Locate many large moth caterpillars like the tomato sphinx caterpillar by the frass below the plant they are eating. Carefully look above the piles of frass for damaged leaves and the caterpillar. Many caterpillars feed on large trees and locating them is next to impossible unless there is an infestation. Consult local gardeners, scientists and other resource people to find good places to find caterpillars.
Most larvae of butterflies and moths eat plants. Many species are very selective about what they will eat and may feed on only one species of plant in their lifetime. Adults usually feed on the nectar of flowers, but some do not feed at all. Some larvae feed on fabric or stored grains.
Lepidoptera larvae are usually found on their food plant, but may be well hidden. They can often be found by looking for damaged leaves. Frass may be visible around the base of the plant or under a tree. Pre-pupal larvae often wander off of the food plant in search of a good place to pupate.
Both larval and adult butterflies and moths are often highly colored. Sometimes the colors are bright and are intended to warn away potential predators. Often, this indicates that they taste bad to a predator. Other times the bright colors are meant to attract mates. Some are colored to look very much like a food plant in order to help the insect hide. Eggs of lepidoptera often have very elaborate shells, and may be either brightly colored or cryptic. The egg shell or chorion, are usually very hard to prevent predators from eating them.
The adults of butterflies and moths are well known for their beauty. They provide food for many other animals. Some species are active pollinators.
Larvae of lepidoptera can be harmful when they eat crops, and when their numbers get to be very large, as happens with the Gypsy moth. In general, however, the larvae of butterflies and moths do very little harm, and, are important in maintaining controlled plant growth.