When butterflies emerge from their chrysalises, the final stage in their lifecycle occurs: emerging as adults. At first their wings appear wet and crumpled; however, after some time the butterfly begins pumping a liquid called hemolymph into its wings until they dry up sufficiently for flight.
Once a caterpillar reaches full maturity, it forms an exterior hard cover called a chrysalis or cocoon which may take several days up to several months depending on its species.
Eggs
At the core of every butterfly life is its egg. Once laid by female butterflies, these eggs will often be laid onto plants which will provide food sources as caterpillars evolve into butterflies or moths. After being laid on plants by female butterflies, these eggs then undergo metamorphosis or changes referred to as metamorphosis which varies between insect species; most insect species typically experience four stages – egg, larva, pupa and adult.
An egg in development is known as an oocyte. When developing, an oocyte goes through meiosis – a highly specialized form of cell division in which two identically genetic material cells divide to become fertilized to produce new eggs. Most oocytes will stop at Prophase I before fertilization takes place but some may stop at other points during meiosis.
An oocyte needs special chemical messengers in order to fertilize. These chemical messengers, called cyclin and cyclin-dependent kinases, allow eggs to communicate between one another. When these protein complexes become active, an oocyte begins to divide, producing daughter cells which then go on to fertilize each other.
As an egg develops, it builds a thick protective coating of albumin fluid and hard shell made up of calcium carbonate deposited by its mother hen in her body, passing through an organ called the shell gland and solidifying. Meanwhile, its yolk features a special membrane to absorb oxygen while excrete waste products – all this waste being collected into an allantois sack for storage.
Once an egg is formed, it can begin to produce embryonic tissues and a heartbeat. Temporary organs also develop within it to provide nourishment, protection, and respiration – these include the yolk sac, amnion, and allantois. Furthermore, its cytoplasm contains tiny cortical granules that lie just underneath its plasma membrane – if sperm enters before activating these granules then the embryo will remain sterile.
Caterpillar
Butterflies (and moths) experience an extensive metamorphosis during their short lives. From tiny eggs found on host plant leaves to hatching into baby caterpillars – commonly referred to as larvae – that gorge themselves on leaves to eat, they then continue eating up their hosts to increase in size exponentially! Over the course of their short lives they may reach up to 100x larger! Occasionally their stretchy skin becomes too tight, forcing them to shed it for new, larger skin beneath. Each stage is known as an Instar!
At some point, a caterpillar will consume enough nutrients to trigger its internal chemical processes to begin developing a chrysalis. When this happens, ecdysone hormone is released instructing it to molt. When its skin no longer fits correctly it stops eating, hangs upside-down from a leaf or branch and either spins a silken cocoon or changes into an elaborate chrysalis.
At this stage, a caterpillar will shed its skin several times to ensure that the parts it will use to form its butterfly form are in proper proportions. Once ready to become a fly, the caterpillar will look for a secure yet covered spot to pupate (either near its food source, such as on a branch, or more inconspicuously such as hollow logs or bark) where it can pupate safely and covertly.
Once inside its chrysalis, the caterpillar will remain safe from predators and environmental elements until it emerges to its adult form. Once emerge, however, it will head out into the world and search for its ideal mate.
Though it may appear effortless, the transformation from caterpillar to butterfly can be an incredible journey. Each stage a caterpillar passes through is an incredible demonstration of nature’s immense power of transformation; no wonder so many children enjoy studying and watching butterflies go through their cycles of growth!
Pupa
Once a caterpillar has reached maturity, it leaves its host plant to search for an appropriate spot to begin its next stage of life. After finding such a safe space, it forms a pupal skin or chrysalis that will protect it as it undergoes profound change. For about one week after entering this stage, no eating or movement occurs as digestive juices break down its tissues to form tissue soup from which wings, legs, eyes, mouthparts and genitalia emerge from.
Once a butterfly or moth has released the chemical that causes its wings to unfurl, they hang upside down from its cremaster – an appendage covered in hooks that serves to hold it steady while it transitions to adult form.
During the pupal stage, special cells that were dormant during larval development begin to rapidly divide and multiply, eventually producing adult wings veins and structures such as tail veins; some original larval cells may even provide energy during this process.
Caterpillars may spend the winter inside their chrysalises, skipping an entire year of development and saving a step. Unfortunately, this puts them at increased risk from predators; most multivoltine species that overwinter pupate during spring rather than fall.
No matter if a pupa develops during summer or overwinters to develop later, its hormonal state influences its final coloration. Direct summer pupae usually turn out green while overwintering pupae are more likely to turn brown [31] .
Some aquatic Diptera such as mosquitoes, fleas and ticks remain mobile during their pupal stages; however, most remain attached to substrate by either special adhesive discs on their backs or silk tubes made from salivary gland silk (e.g. Culicidae and Simuliidae). While aquatic Diptera can swim freely they cannot fly.
Adult
At the peak of its lifecycle, butterflies reach adulthood – the stage in which they are free to feed on food sources, mate with another butterfly and lay eggs. Adult butterflies differ dramatically from larva and caterpillar stages with long wings capable of flight; one amazing aspect of nature that brings about this change.
Female butterflies lay their eggs on host plants, where the eggs will then be devoured by tiny caterpillars that hatch within six to eight days later and feed on the leaves of that host plant until reaching full size and reaching pupal stage (shedding of skins several times, growing new layers and moulting). Once at full length, caterpillars will form cocoons to protect themselves while becoming adult butterflies.
At this stage, special cells present in caterpillars are transformed into the wings and other adult parts of a butterfly, including its folds and antennae. Chrysalises may be found on rocks, tree branches or underneath leaf litter – however this protection from predators may not apply in butterfly species.
As it emerges from its chrysalis, a butterfly emerges wet and wrinkled with soft wings folded tightly against its body. After resting a while longer, the butterfly begins pumping hemolymph into its wings in order to harden them, before flying off in search of a mate.
Male butterflies typically find mates by dancing around perched females and extending their abdomens toward them until they meet, at which time they connect their wings in an expression of acceptance before mating via exchanging sperm exchange and gifting nutrients so the female can prepare to lay more eggs.