The natural world is full of wondrous things, one of the most marvelous being the butterfly's life cycle, a metamorphosis that involves a fairly innocuous egg changing into the beautiful, iridescently-hued butterfly.
It all begins with the mating of two butterflies, which is achieved by the female sitting in some strategic location and releasing certain scents in order to attract the male of her species. Similar to other species, before the actual mating takes place, there is a courtship routine that occurs. Depending on the species, some females may sit with their wings positioned in a certain way, or they may fly in spiraling patterns. The mating, of course, enables the fertilization of the eggs.
Once the mating is accomplished, which can last for several hours in some species, the male goes in search of another female, while the female lays her eggs after locating a suitable plant to do so. This is important because once the caterpillar emerges, it will only feed on particular types of plants. The female can detect a suitable plant that can serve as a source of food for the caterpillars by the sensilla on her legs.
While some species of butterflies, known as polyphagous, can lay their eggs on different species of plants, others, known as oligophagous, will do so in plant species that are similar, and a third type, known as monophagous, will lay their eggs only on a single plant species.
The Ovum or Egg
The eggs are sometimes laid in bunches, while at other times, single eggs may be laid in a scattered fashion. These strategies are used in order to help the survival of the eggs. For example, when laid in a bunch, a predator might miss a few eggs in the group, and likewise, when they are laid in a scattered manner, the predator may only eat up a few, leaving the others to develop. The eggs of various species come in various colors, patterns, and shapes. The embryo grows inside the egg, which can take 2-3 weeks. However, in some species, this stage can last over the winter, which means that the caterpillars only emerge the following spring. After the caterpillar is formed fully, it chews a hole through the eggshell and comes out.
The Larva or Caterpillar
When they hatch from their eggs, the caterpillars are tiny in size, measuring just a few millimeters in length. However, they grow quite rapidly because they spend most of their time just feeding themselves. During this phase of growth, the caterpillar sheds its skin four times, with each new skin being larger as compared to the previous one, in order to enable its growth. This is also the phase during which the caterpillars are susceptible to being devoured by predators, and hence, they are usually camouflaged well to blend in with the plants they live and eat on.
There are organs near the jaws of the caterpillars from which they can produce a kind of silky thread which they use for various purposes. For example, they can use it to anchor themselves to a plant, while others use it for resting between periods of feeding. Some species even use it to make a web within which several caterpillars live, only separating when they grow fully.
On reaching full growth, the caterpillars start hunting for a suitable location for pupation.
The Pupa or Chrysalis
The manner in which an energetic caterpillar turns into a motionless pupa is one of the great marvels of nature. At the final stage of the last instar (a phase between the molting process of the caterpillar), there is one more change that occurs on its skin, with it splitting to uncover a glistening, wet organism that looks like a rounded form of the original caterpillar. In about two hours, the pupa forms fully, with the outer layers drying and hardening. The butterfly generally does not spin a cocoon with its silken thread in its pupal stage, but uses it to fasten itself to a plant. Since this is also the stage when it is most vulnerable to predators, the pupa is camouflaged well.
This stage lasts for about a couple of weeks, although some species hibernate over the winter during this phase. This is also the phase when the final metamorphosis occurs inside the pupa, with cells growing to create the unmistakable characteristics of an adult butterfly. Just prior to the butterfly emerging, the skin of the pupa becomes transparent, making visible the patterns of the wings through it.
The Adult Butterfly
At the end of the whole process of metamorphosis, the fully-formed butterfly emerges from its pupal case, pulling itself out and then hanging head down, its wings limp and moist. Almost at once, it starts spreading its wings by pumping blood forcefully into the blood vessels in them. When the wings are able to spread to their optimum size, they are dried and hardened. Once that is done, the blood is pumped out of the wings, thus making them not only strong, but also light, and the butterfly is ready to take its first flight. The new butterfly will first look for nourishment and then a mate, to begin the life cycle all over again.