The Life Cycle of a Butterfly
Like all insects, a butterfly begins its life as an egg. As soon as the larva hatches, it begins eating. The larva of a butterfly is called a caterpillar. The caterpillar eats the plant it lives on, chewing away at the leaves. A caterpillar’s job is to grow, grow, and grow some more. If a human baby grew at the same rate as a caterpillar, it would end up the size of a school bus! When a human grows, her skin grows with her. A caterpillar has an exoskeleton – their skin can‘t get any bigger. So each time they grow, they need to get rid of their old exoskeleton and grow a new one. This process is called molting. They crawl out of their old skin, grow, then new skin hardens into an exoskeleton. Each of these stages is an instar. The average caterpillar goes through 4 or 5 instars before it is ready to pupate. When a caterpillar pupates, it becomes a pupa, which is in a chrysalis. The pupa is the life stage of great change. The whole body is rearranged from the cellular level up. What once was a long, skinny, wingless eating machine will become a slender, winged, flying butterfly. The amount of time it takes to pupate depends on the type of caterpillar. When the adult butterfly emerges from its chrysalis, its wings are shriveled and wet. The butterfly pumps hemolymph, insect blood, into the wings, then lets them hang straight while they dry and harden. As an adult, the butterfly will not grow any more. It eats with a proboscis, sipping nectar, or sometimes tree sap or fruit juice, through a long tube-like mouth. The adults mate, the female lays eggs on a host plant, and the adults die. A butterfly’s whole life cycle can last as little as 30 days or as long as 2 years. At any point in its life cycle, an insect can enter diapause. Like the pause button on a remote stops a movie, diapause suspends the insect’s development until conditions in the environment are better. For example, many butterfly species spend the winter as caterpillars. As the weather grows colder, and food becomes scarce, the caterpillar slows down and eventually stops functioning. They will usually enter diapuase in a sheltered area to protect them from the elements. As the weather warms, the days become longer, and plants start to grow, the diapause ends and they resume growing and developing. Some butterflies enter diapause during the hottest part of the summer.
Most species of butterfly use only a few specific plants as hosts. The plants are often in the same family. Some butterflies use only one species of plant as a host for its caterpillars. The adult female butterfly will only lay her eggs on a host plant. She uses her feet to “taste’ the plant to see if it is the correct species.
University of Rhode Island GreenShare Factsheets: Butterfly Gardens