A butterfly starts its journey as an embryonic egg that has been fertilized, then hatches under favorable environmental conditions into an egg larva or caterpillar stage.
A larva eats and develops, gradually shedding its skin four or five times as it goes along; this process is known as moulting.
A larva then forms a pupal case from its own skin to protect its pupation process, then moves into its own chrysalis for transformation into butterfly form.
Egg
A butterfly’s life cycle begins when female butterflies lay their ovular eggs on a leaf of a plant, where they hatch into larvae (caterpillars). Larvae feed on leaves of their host plant until reaching full size before metamorphosing into pupal stages called pupals – this remarkable transformation lasts between weeks or months depending on which species of butterfly it belongs to.
At this stage, a caterpillar molts several times to shed its skin and change into its adult form. Caterpillars form protective cases called chrysalises that they attach to suitable spots: this could include hanging from a branch, burrowing into soil or hiding itself within leaves; it’s essential that its caterpillar finds somewhere safe from predators or weather while still allowing it to feed during its transformation process.
Once the caterpillar reaches its final pupal form, it becomes a chrysalis and closes itself up, seemingly resting. But in reality, the chrysalis is actually a cocoon from which its adult butterfly will eventually emerge as an adult butterfly.
As the caterpillar prepares to become an adult, it releases a fluid which hardens into its final wing shape. Once ready to fly, they will break open their chrysalis and emerge as fully grown butterflies known as imagos.
This is the result of an extended process, yet one which yields beautiful butterflies. A butterfly’s life cycle takes approximately one year from egg to adulthood and involves four distinct stages of metamorphosis; to help students understand this parallelism better, have them draw pictures of themselves as babies before creating a Venn diagram that compares these stages against ours.
Larva
As soon as a butterfly egg hatches it transforms into what is known as its larva stage, lasting from several days to several months depending on species. Fertilized eggs are laid by female butterflies on specific plants that will provide food sources for the developing larva. Butterfly eggs come in various shapes including bullets, discs and turbans with pearly white colorations ranging from bark brown and rusty red hues for maximum camouflage from predators.
Once a larva has hatched, it starts growing rapidly. After eating its host plant, the larva eats itself before splitting its skin several times to grow bigger and store food during this period. Some species use brightly-colored larvae as warning signals against predators; milkweed butterfly larvae have a particularly unpleasant taste due to eating their host plants.
As the larva develops, special cells which will eventually become its legs, wings and eyes begin to take form. At this stage it alternates between feeding and resting periods. Spines, false eye spots or other markings may also be added for protection. Most species feed individually but some eat communally.
At the conclusion of an instar, larval development prepares for its next transformation: Feeding ceases, its gut is cleansed of any remains and it sheds its outer skin to enter pupal phase; often its skin provides better camouflage than that found on larvae and is smooth and shiny.
The pupal stage usually lasts between one week and over one year, depending on species. Once inside a pupal stage, caterpillars select a safe location such as leaf litter or underside of log or branch to transform themselves into butterflies. Once they enter this final molt called chrysalis they form another hard shell called a chrysalis that provides shelter during its development and eventual metamorphosis into adulthood.
The chrysalis may differ in appearance from its larval form, but serves the same function: protecting a butterfly while its wings develop. Once ready, they will crawl out of their protective shell and fly off in search of a mate.
Pupa
The pupal stage of metamorphosis is a resting period during which nymphs undergo major cell reorganization to become fully mature insects, in the case of butterflies and moths this results in beautiful adult butterflies or moths. Pupal protection from predators and other dangers often includes camouflaging against their surrounding environment or creating a protective cocoon, known as tying.
At maturity, caterpillars achieve it through multiple molting cycles. At each instar’s end, they shed their old cuticle and grow a new one made up of tough chitin-protein mixture. At the same time, neurohormones trigger this development, as does splitting open their new cuticle to expose soft epidermis underneath that will begin producing its own hard cuticle; all while the mixture between chitin-protein cuticle hardens and darkens over time.
Chitin hardens to form a tough outer shell known as the pupal skin. At this stage, larval butterflies and moths can either erupt from this cuticle or spin a silk button to fasten itself onto a leaf, twig, or object for pupation. Sometimes a caterpillar will form a cocoon before becoming a pupa; however, in most butterflies and moths this step is not required; the cocoons produced by certain moth caterpillar species provide fine textiles.
Pupae are generally defenseless and immobile larvae. To protect themselves from being eaten by predators, some insects form cocoons around their pupae while others hide under leaves or objects; Lycaenid butterflies employ this strategy while some social hymenopterans, like bees, provide protection for their pupae by creating cocoons within their hives.
Holometabolous insects exhibit rapid and dynamic development of their imaginal discs that forms wings, antennae, legs, mouthparts and other body structures. This rapid expansion is caused by a temporary pause in Br-C enzyme activity normally activated by JH in the final larval stage; when pupation comes around it’s suppressed during pupation thus permitting continued development without interference from degrading larval organs.
Adult
The larva (or nymph) stage of many Lepidopteran species such as butterflies is the feeding and growth stage, often featuring intricate patterns or colors. This stage of development is marked by multiple growth spurts or “molts”, in which the caterpillar sheds its outer skin multiple times. As it rapidly develops, more nutrients are required to fuel its rapid development; to access these essential resources quickly enough, nymphs eat off old skin in order to obtain them. Once its body can no longer accommodate all the food it consumed, a caterpillar stops eating. Once fed its final meal, the nymph looks for somewhere suitable to go into pupal stage. The pupal stage (also called chrysalis) of butterflies’ development consists of an immobile hard shell-like enclosure which varies in color to mimic its surroundings for camouflage purposes. At this third transformative stage, caterpillars reorganize their cells and structures into those necessary to become an adult butterfly; this process may take weeks, months or even years and some butterflies overwinter in this stage (known as diapause); examples include mourning cloaks (Nymphalis antiopa) and eastern commas (Polygonia comma).
The chrysalis may appear to be nothing more than a protective cocoon for the caterpillar’s old skin, but inside are vast transformations taking place. Specialized cells from larva begin rapidly replicating, eventually becoming the legs, wings and eyes of an adult butterfly using energy stored from original larva cells.
Once a butterfly is ready to emerge from its chrysalis, it will open it and crawl out, hanging upside down while fluid from its body inflates its wings – this process may take up to two hours. When its wings have dried and stretched properly, the butterfly can fly off to feed, find a mate, lay eggs, and repeat its cycle of existence.
While each stage of metamorphosis appears distinct, they all occur simultaneously within an insect’s lifecycle and, therefore, metamorphosis refers to all stages of development, not only egg, larva and pupal stages.