A caterpillar chewing through a leaf and the moth fluttering past a porch light look like two different animals, yet they’re the same creature living out separate chapters of one life. That transformation is the whole point behind the many types of insects that morph: each species rebuilds its body, sometimes completely, to match a different job at a different age. Some insects skip the dramatic wardrobe change and simply grow bigger with every molt, while others dissolve almost entirely inside a pupal case and rebuild from scratch.
Entomologists sort this process into two broad patterns: incomplete metamorphosis, where nymphs already look like miniature adults and simply molt into bigger versions of themselves, and complete metamorphosis, where a legless larva pupates and emerges as a wholly different-looking adult. This pattern shows up well beyond insects alone, and the broader biological picture is covered in this guide to animals that go through metamorphosis. The twenty insect groups below span both strategies, from moths that pupate inside silk cocoons to cicadas that spend over a decade underground before molting into a winged adult.
| Metamorphosis Type | What Happens | Examples Covered Below |
|---|---|---|
| Incomplete (hemimetabolous) | Egg hatches into a nymph that resembles a small adult; nymph molts repeatedly, growing wings gradually | Grasshoppers, earwigs, dragonflies, termites, aphids, katydids, cicadas, mantises, crickets, mayflies |
| Complete (holometabolous) | Egg hatches into a larva with a totally different body plan; larva pupates, then emerges as an adult | Moths, butterflies, beetles, true flies, fleas, lacewings, wasps, bees, ants |
| Gradual (ametabolous-adjacent) | Nymphs are nearly identical to adults, differing mainly in size and reproductive maturity | Cockroaches |
1. Moths
Moths rebuild their entire body plan during complete metamorphosis, trading a crawling caterpillar for a dust-winged adult built for night flight. The egg hatches into a caterpillar that spends most of its life eating, then spins a silk cocoon and pupates inside it before emerging with wings, antennae, and a coiled feeding tube in place of chewing jaws.
The giant silk moths illustrate this change dramatically. The luna moth (Actias luna) spends its larval stage as a plump green caterpillar before wrapping itself in a papery cocoon, emerging weeks later with pale green wings spanning several inches. Not every moth caterpillar eats leaves, either; a few fabric-damaging moth species develop inside wool sweaters and carpets instead of on garden plants.
Pro Tip: A silk cocoon wrapped in loose fiber usually belongs to a moth, while a smooth, hardened chrysalis hanging exposed on a twig almost always belongs to a butterfly.
2. Butterflies
Butterflies follow the same four-stage complete metamorphosis as moths, but their pupal stage is a hardened chrysalis formed from the caterpillar’s own skin rather than a woven cocoon. Arizona offers an unusually good window into this process, since the state supports one of the richest butterfly faunas in the country across its desert, mountain, and riparian habitats.
The state’s official insect, the two-tailed swallowtail (Papilio multicaudata), is one of the largest butterflies in North America, with a wingspan that can stretch past five inches on a full-grown adult. Its caterpillar feeds on ash and chokecherry leaves before pupating into the yellow-and-black-striped adult familiar to hikers across the Sonoran Desert. Monarchs (Danaus plexippus) pass through Arizona on their seasonal migrations too, and their caterpillars’ dependence on milkweed makes them one of the most studied examples of complete metamorphosis among native butterflies in Arizona and the broader Southwest.
3. Cockroaches
Cockroaches undergo incomplete metamorphosis, but their nymphs look almost identical to the adults from the moment they hatch, only smaller, paler, and wingless. Each molt simply makes the nymph larger and darker until wing buds appear in the final instars before the adult molt.
The American cockroach (Periplaneta americana), common in basements and sewer systems across the United States, can take over a year to mature through a dozen or more nymphal instars. Not all roaches are household pests, though. The Madagascar hissing cockroach (Gromphadorhina portentosa) is kept as a classroom and hobbyist pet precisely because its slow, gradual metamorphosis makes each life stage easy to observe.
4. Beetles
Beetles make up the largest order of insects on Earth, and nearly all of them undergo complete metamorphosis from a grub-like larva to a hard-shelled, armored adult. The larval stage does the bulk of the feeding and growing, while the pupal stage rebuilds the body around a new set of wing covers, or elytra.
A garden favorite, the seven-spotted lady beetle (Coccinella septempunctata), starts life as a spiky, alligator-shaped larva that hunts aphids before pupating into the familiar round, spotted adult. Beetle diversity reaches its peak in tropical forests; the sheer variety of beetle species found throughout insects in the Amazon rainforest dwarfs anything seen in temperate gardens, with many species still undescribed by science.
5. Grasshoppers
Grasshoppers are textbook examples of incomplete metamorphosis. The nymphs, sometimes called hoppers, emerge from the egg already shaped like miniature adults and simply molt five or six times, growing wing pads a bit larger with each stage until the final molt produces fully functional flight wings.
The differential grasshopper (Melanoplus differentialis) is one of the most widespread species in the country, thriving in open grassland and crop fields. Large grasshopper populations are a familiar sight across the dry rangelands tied to insects in Texas, where warm, long growing seasons let several generations develop in a single year.
6. Earwigs
Earwigs also rely on incomplete metamorphosis, with nymphs that look like tiny, wingless versions of the pincer-tailed adults. They molt four to five times before reaching maturity, gradually developing the hardened forewings that fold over the hind wings in adults.
The European earwig (Forficula auricularia), now established throughout much of the United States, is identifiable by the curved cerci at the tip of its abdomen, used for defense and occasionally for grooming. Earwigs are one of several groups covered in this roundup of insects that start with E, which explores other species sharing the same gradual nymph-to-adult pathway.
7. Dragonflies
Dragonflies spend the vast majority of their lives underwater as nymphs, known as naiads, before an incomplete metamorphosis sends them airborne. The aquatic nymph breathes through gills, hunts other invertebrates, and molts repeatedly before crawling out of the water for its final molt into a flying adult.
Research on the endangered Hine’s emerald dragonfly (Somatochlora hineana) shows just how long this aquatic stage can last and how brief adulthood is by comparison. According to a Wikipedia summary of the species, the adult stage lasts only four to six weeks, while the dragonflies overall live for two to four years once the nymph stage is counted. Most of that lifespan, in other words, happens underwater rather than in flight. Dragonflies share this aquatic nymph strategy with several other insects that live in water.
8. Termites
Termites undergo incomplete metamorphosis, but their nymphs follow an unusual path: rather than maturing straight into winged reproductive adults, many nymphs develop into sterile workers or soldiers instead, a caste system that distinguishes them from most other gradually metamorphosing insects.
The eastern subterranean termite (Reticulitermes flavipes), the most economically damaging termite species in the United States, maintains colonies where only a small fraction of nymphs ever molt into winged reproductive swarmers. The rest remain as workers feeding the colony on cellulose, which is why termite damage so often turns up among the broader list of insects that eat wood.
Common Mistake: Termites and ants are often confused because both live in large colonies, but ants undergo complete metamorphosis with a legless larva and pupa, while termite nymphs never pass through a grub-like larval stage at all.
9. Aphids
Aphids go through incomplete metamorphosis at remarkable speed, with nymphs reaching adulthood in as little as a week under warm conditions. Many generations skip the egg stage entirely, since female aphids can give live birth to genetically identical daughters through parthenogenesis without ever mating.
The green peach aphid (Myzus persicae) is one of the most widespread crop pests in the world, and its nymphs molt four times before becoming winged or wingless adults depending on population density and food supply. Backyard growers dealing with aphid outbreaks are usually also managing several other soft-bodied pests covered among common insects in Ohio gardens.
10. Katydids
Katydids follow the same gradual, incomplete metamorphosis pattern as their grasshopper and cricket relatives, with nymphs that resemble small, wingless adults from the moment they hatch. Each molt adds a bit more wing development until the final adult stage produces the long, leaf-shaped forewings used for both camouflage and sound production.
The true katydid (Pterophylla camellifolia) is famous for its rasping, two- or three-note call, produced by rubbing specialized structures on its forewings together rather than by vocal cords. That nighttime chorus places katydids firmly among the insects that make noise across summer woodlands in the eastern and midwestern United States.
11. Cicadas
Cicadas take incomplete metamorphosis to an extreme, with nymphs that burrow underground and feed on root fluids for years before ever seeing daylight. Periodical cicadas in the genus Magicicada are the most famous example, spending either thirteen or seventeen years underground depending on the species.
According to a Wikipedia overview of periodical cicadas, mature nymphs emerge between late April and early June after their prolonged developmental phase, and the adults are active for only about four to six weeks before dying. Clemson Cooperative Extension notes that these insects undergo incomplete metamorphosis, and eggs hatch into nymphs that go through four instars while feeding underground on tree roots before their final molt into a winged adult.
Key Insight: Not every cicada waits over a decade to emerge. So-called annual cicadas spend only two to five years underground, with some adults appearing every single summer even though no individual actually completes its cycle in one year.
12. Praying Mantises
Praying mantises undergo incomplete metamorphosis, hatching as tiny nymphs that already carry the characteristic raptorial front legs used to snatch prey. They molt five to ten times, shedding their exoskeleton as they outgrow it, before the final molt produces functional wings on the adult.
The Carolina mantis (Stagmomantis carolina), one of the few mantis species native to the United States, is commonly confused with the larger, introduced Chinese mantis in backyard gardens. Mantis egg cases, called ootheca, are popular with hobbyists who raise the nymphs indoors, making mantises a regular entry among insects kept as pets.
13. True Flies
True flies undergo complete metamorphosis, with legless larvae known as maggots that look nothing like the winged adults they become. The maggot feeds voraciously, molts through several instars, then pupates inside a hardened case before emerging with a single pair of functional wings.
The housefly (Musca domestica) can complete its entire life cycle from egg to adult in under two weeks during warm weather. Mosquitoes belong to this same order, and their larvae develop in standing water before adults emerge to feed, which places them among the better-known insects that suck blood.
14. Fleas
Fleas complete a full four-stage metamorphosis despite living much of their lives hidden in carpet fibers, bedding, or animal fur. Eggs hatch into worm-like larvae that feed on organic debris rather than blood, then spin a cocoon where they can remain dormant for weeks before pupating into the biting adult.
The cat flea (Ctenocephalides felis) is the species most commonly found on household pets across the United States, and its resilient cocoon stage is why flea infestations can resurface weeks after a home has seemingly been treated. Like mosquitoes, adult fleas feed on blood, placing them firmly among other blood-feeding insect species.
15. Neuropterans (Lacewings and Antlions)
Lacewings and antlions undergo complete metamorphosis, with predatory larvae that look almost nothing like the delicate, net-winged adults they eventually become. Lacewing larvae are sometimes called aphid lions for their habit of skewering aphids on curved, hollow jaws, while antlion larvae dig small conical pits in sandy soil to ambush passing prey.
The green lacewing (Chrysoperla carnea) pupates inside a silken cocoon spun from its own larval silk glands, emerging days later with the pale green wings familiar around porch lights. Antlions in the genus Myrmeleon can take a year or more to complete their larval stage, a slow timeline shared with several other insects in Canada that must wait out long, cold winters between molts.
16. Wasps
Wasps undergo complete metamorphosis, hatching from eggs into grub-like larvae that are fed and cared for by adult workers in social species, or provisioned with paralyzed prey in solitary species. The larva pupates inside a paper or mud cell before emerging as the familiar narrow-waisted, winged adult.
Paper wasps in the genus Polistes build open, umbrella-shaped nests under eaves and porch ceilings throughout the United States, including a common presence among insects in New York neighborhoods each summer. Their larvae remain in individual paper cells until pupation, visible as capped cells toward the center of an active nest.
17. Bees
Bees share the same complete metamorphosis pattern as their wasp relatives, with legless larvae that are fed by adult workers before sealing themselves into a wax or paper cell to pupate. The transformation inside that cell is total, turning a blind, grub-like larva into a fully winged, compound-eyed adult in roughly two to three weeks.
The honey bee (Apis mellifera) is the most economically important example, with colonies that rear thousands of larvae simultaneously across wax comb cells. Bees are also frequently grouped with other insects with stingers, since only the adult stage develops the modified ovipositor used for defense.
18. Ants
Ants undergo complete metamorphosis just like bees and wasps, with legless larvae that depend entirely on adult workers for feeding and grooming. The larva pupates, often inside a cocoon depending on the species, before emerging as the familiar six-legged, segmented adult.
Carpenter ants (Camponotus pennsylvanicus) build galleries inside damp or decaying wood, and their larvae are tended in brood chambers deep within the colony until pupation is complete. Ant colonies vary widely in temperament, and identifying aggressive foragers is the focus of this guide to types of ants that bite.
19. Crickets
Crickets undergo incomplete metamorphosis, with nymphs that emerge from the egg already shaped like small, wingless adults. They molt eight to ten times over several weeks, gradually developing the wing pads that will eventually produce their signature chirping call.
The field cricket (Gryllus pennsylvanicus) produces its familiar nighttime song by rubbing a scraper on one forewing against a file-like ridge on the other, a behavior that only becomes possible once the final adult molt is complete. Crickets rank among the most recognizable insects that make noise in backyards and fields across the country.
20. Mayflies
Mayflies undergo an unusual version of incomplete metamorphosis that includes an extra transitional stage most other insects skip entirely. The aquatic nymph molts repeatedly underwater, then emerges as a winged but sexually immature subimago before molting one final time into the reproductive adult.
In the genus Hexagenia, one of the most common burrowing mayfly groups in North American rivers and lakes, the insects are hemimetabolous, with immature aquatic stages lasting between one and two years before the short-lived, winged adult stage begins, according to a Wikipedia entry on the genus. Mayfly nymphs share their underwater habitat with dragonfly naiads and other insects that live in water, though the mayfly’s winged adult stage is by far the shortest of any insect on this list, often lasting only a day or two before it dies.
Whether an insect molts gradually into a slightly bigger version of itself or dissolves completely inside a pupal case, metamorphosis solves the same basic problem: it lets one animal do two very different jobs at two different ages. A soft, crawling larva can specialize in eating and growing, while a hardened, winged adult specializes in finding a mate and reproducing. Watching for molted exoskeletons, pupal cases, or nymphs tucked under bark is often the easiest way to catch this transformation happening in real time, right in a backyard garden or local park.