A person may fear caterpillars because they resemble worms that have 12 eyes and what appear to be dozens of legs. These insects are not worms, they have fewer legs than you think and they cannot harm you. Caterpillars are simply the moths and majestic butterflies of tomorrow trapped in worm-like bodies today. Over 20,000 types of caterpillars exist and new ones are still being discovered. Metamorphosis, the fascinating life cycle that transforms these crawling creatures into insects that fly, begins with mating.
From Courtship to Conception
A male butterfly, which often dies after mating, seeks females of its own species in several ways. For example, it might look for those that have specific wing colors and positions. Female butterflies lay eggs on plants, leaves and stems -- locations that provide food for larvae after they break through the eggs. The pregnant female is picky about the food her offspring will eat. To find the right plant species, she may scratch a leaf with her feet and whiff the odor. This helps her identify the species she seeks. Caterpillar eggs are small and come in various colors.
From Eggs to Caterpillars
Newborn caterpillars, also called larvae, arrive with humongous appetites. Because they'll need plenty of energy to complete their metamorphosis, their primary activity is eating. Surviving as a caterpillar can be challenging because so many creatures want to devour you. Predators include birds, parasites -- such as the tachinid fly -- and spiders. Weslayan University and UC Irvine researchers discovered that caterpillars who eat no more than two plant species hide more effectively from bird predators than caterpillars who eat a variety of foods. Molting occurs when the caterpillar's tough skin, which does not stretch, sheds. This process may occur up to five times in the caterpillar stage.
Time to Hide: The Transformation Begins
One day, a caterpillar attaches itself to a support object, such as leaf or twig, and enters the pupa stage. If the caterpillar is to become a butterfly, it transforms into a shiny chrysalis. If the caterpillar's destiny is a moth, it wraps itself in a cocoon. Inside these protective shells, the insect secretes digestive juices that dissolve much of its body. The only parts that remain are the imaginal discs formed when the caterpillar was in its egg. Each disc corresponds to a body part the caterpillar will need as a butterfly or moth. After all tissue except for the imaginal discs is dissolved, the discs begin forming the moth or butterfly's body parts.
Freedom Comes: Flight at Last
A butterfly or moth finally forms in the pupa and breaks through to its new world. The time it takes to do that varies from a few days to over a year depending on the species. If predators don't eat them during this adult stage, butterflies in the wild can live between 7 and 10 days. Some, however, may survive up to 6 months when they eat pollen, rotten fruit and animal excrement instead of nectar. They live longer because these foods provide them with important amino acids. As moths and butterflies mate, they produce new caterpillars who continue the never-ending metamorphic cycle.
- University of Kentucky Department of Horticulture: All About Butterflies
- University of California Agriculture & Natural Resources: Caterpillar Management: Caterpillar Natural Enemies
- Florida Museum of Natural History: Butterfly Q&A
- Scientific American: How Does a Caterpillar Turn into a Butterfly?
- University of California, Irvine: For Caterpillars, Diet Is Destiny
- XiXinXing/XiXinXing/Getty Images