Praying Mantid Eggcase

What is the difference between complete and incomplete metamorphosis in insects?

Incomplete and complete metamorphosis differ in the number of life cycle stages insects go through during their transformation from egg to adult. Complete metamorphosis has 4 life cycle stages and incomplete metamorphosis has 3 life cycle stages.

Complete Metamorphosis

Complete metamorphosis has four distinct life cycle stages: egg, larva, pupa and adult. Examples of insects that go through complete metamorphosis are butterflies, silkworms, mealworms and ladybugs. The larva can be worm-like, although you can still see the six legs. The larvae for moths and butterflies are called caterpillars. Maggots are the larval stage of flies. The larvae eat constantly and grow rapidly. A hard, protective case forms around the larva…this is the pupa stage. The pupa stage for a butterfly is called a chrysallis. The pupa stage for a moth is called a cocoon.

Incomplete Metamorphosis

Incomplete metamorphosis only has three life cycle stages: egg, nymph, adult. The nymph looks similar to, but a smaller version of, the adult. The nymph is also wingless. Examples of insects that go through incomplete metamorphosis are stinkbugs, earwigs, crickets, grasshoppers, cockroaches, ants and praying mantids.

When butterflies emerge from the chrysalis, they are considered adult butterflies.  Care and feeding of adult butterflies is important to successfully complete a butterfly life cycle experiment.  Adult butterflies do not have jaws that allow them to chew plant material as they did when they were caterpillars.  Instead, they have a long, straw-like tongue called a proboscis through which they can consume liquid material. Butterflies are an example of an insect that goes through complete metamorphosis.

The caterpillars diet normally consists of one type of plant, depending on the species. The most popular butterfly used in classroom studies is the Painted Lady, Vanessa cardui. They are available through many different sources and they are a cost effective option. In nature, the larva feed on the mallow plant. In classroom studies, a prepared diet is the best option. The caterpillars each constantly during this time period. The larval stage lasts approximately 4 weeks. The habitat should not be too large as this will make it difficult for the caterpillars to find the food source. If this happens, the larva could starve. One unusual characteristic of the caterpillar is that it has 8 pairs of legs to assist in climbing. After the last molt, only the front 3 pairs will remain.

After the 3-4 weeks spent as a caterpillar, the larva will attach itself upside down and form the crysalis. When the chrysalis has hardened, they should be transferred to a larger container, normally a net type habitat. The filter paper that the larva attaches to can be attached to the top of the net using a paper clip. In 7-10 days, the adult butterfly will emerge.  A few hours will pass before the adult is ready to fly.

When your butterflies emerge from their chrysalis, you should place a shallow container of sugar water into the bottom of their habitat or butterfly net.  They will consume this during the week to 10 days you have them in the habitat prior to release.

Though butterflies can adapt to a fairly wide range of temperatures, it is best to keep their habitat at room temperature and away from direct sunlight through windows.  The time periods listed above can vary depending on the temperature, amount of food and the concentration of larva.