Insects are capable of undergoing a complete change in appearance throughout their life cycles. The process of growth and development from an egg all the way to their adult form is known as metamorphosis. There are two main types: incomplete and complete metamorphosis.
Insects that undergo incomplete metamorphosis have three major life stages: egg, nymph, and adult. They start out as an egg and hatch out as a 1st instar nymph. As the nymph feeds and grows it will periodically have to shed its hard exoskeleton in order to grow more, each time advancing to the next instar. You may notice small wing buds on the backs of a nymph. Each time the nymph molts the wings develop a bit more and will appear larger. After the nymph has entered its final instar it will shed its skin once more becoming an adult, and only in this life stage will it have fully formed wings. The adult body shape will overall resemble that of the nymph stage with addition of wings if present. Some kinds of insects in this category include grasshoppers, dragonflies, cicadas, praying mantises, and cockroaches.
Insects that undergo complete metamorphosis have four major life stages: egg, larva, pupa, and adult. Similar to the other kind, in complete metamorphosis insects start out as an egg but what hatches out is called a larva. Like a nymph, a larva will go through several instars as it feeds and grows. The larval stages of certain kinds of insects have unique names. For example, moth and butterfly larvae are called caterpillars, beetle larvae are called grubs, and fly larvae are called maggots. As the larva develops you may notice the absence of wing buds because in complete metamorphosis the wings develop internally. Once the larva has reached its final instar the next time it molts it will become a pupa. The pupa of a butterfly has a unique name called a chrysalis. Some insects, like many moths, will spin a protective covering around themselves out of silk right before pupating, called a cocoon. They will not eat or move much beyond wiggling back and forth and it is in this life stage that all of the new body parts needed to become an adult will fully form inside. Once the pupa has finished developing it will shed its skin one last time and emerge as an adult with a completely different form compared to its larval stage. Insects that go through complete metamorphosis include flies, beetles, butterflies, and bees.
Puzzling it all together!
Now that you’ve learned about both incomplete and complete metamorphosis try solving our life cycle puzzles! Click the button below to download them. The first puzzle is the life cycle of a large milkweed bug (Ocopeltus fasciatus) which undergoes incomplete metamorphosis and the second puzzle is the life cycle of a black swallowtail butterfly (Papilio polyxenes) which undergoes complete metamorphosis. Print a copy of each puzzle on a separate piece of paper. Use scissors to carefully cut out the puzzle pieces by following the lines. Once you have all of your puzzle pieces from both puzzles mix them together! Using what you’ve learned, can you sort them back out and solve both puzzles?