Butterflies undergo complete metamorphosis, such as four life stages, to transform into an adult from the egg. The caterpillar or larvae is the second phase, which hatch from an egg and is one of the most crucial stages in metamorphosis.
Do All Caterpillars Turn Into Butterflies? All caterpillars do not turn into butterflies because some transform into moths. They become butterflies to reproduce, fly, forage different flower nectar, and find suitable mates. Moreover, the ecdysone and juvenile hormones cause the temporary hindrance of imaginal discs in the caterpillar stage, and caspase enzymes cause the caterpillar self-destruction and form the chrysalis and adult.
This magical and fascinating transformation amazes humans as the caterpillar turns into a different insect with wings, legs, and antennas. Metamorphosis is the Greek word that means change in shape or transformation. Therefore, people also relate them with different symbolic and spiritual meanings.
Do all caterpillars transform into butterflies?
All of them do not transform into butterflies, as some become moths belonging to the Lepidoptera.
Both undergo complete metamorphosis and have four stages: egg, larvae (caterpillar), pupa, and adult. However, the difference occurs in the pupa stage because the butterflies form chrysalis in the third stage, and the moths develop cocoons and spin them to make a silk casing as protection from predators and environmental factors.
It is difficult to guess whether it turns into a butterfly or a moth because they look similar in their developing stages.
For example, my friend has many butterfly species and knows a lot about their appearance and growth details. We often discuss their transformation and life stages because we have some butterflies in captivity. They do not care for their young and fly away after laying eggs.
He said there is a possibility that it either turns into a butterfly or a moth, but not something else. Therefore, some caterpillars in Lepidoptera turn into butterflies, and some into moths.
Why do caterpillars turn into butterflies?
They become butterflies because the caterpillars cannot mate and reproduce to increase their population and diversify genes.
They eat a lot in the developing stage and gain nutrients to develop the essential body organs. They do not have wings and crawl on the ground or plants to feed on the insect larvae and leaves.
They cannot take flights to find suitable mates and lay eggs on the host plants. Their natural growth phenomenon is to turn into adults and grow wings to find mates from their species fellows.
Their bodies are specialized to perform specific functions. For example, butterflies can disperse, fly, migrate, and reproduce, while caterpillars can eat and store nutrients.
The adult species can escape the predators by taking flights because their bodies are agile and can maneuver their flight patterns.
Therefore, it is a must to undergo metamorphosis and complete the life cycle process to develop into an adult.
How do caterpillars turn into butterflies?
The adult butterfly lays eggs on the leaves, and they hatch into caterpillars after a few days to start their life cycle. They transform into caterpillars by the following process.
Shedding and molting by ecdysone hormones
As the caterpillar hatches from the egg, it has thousands of cells, such as imaginal discs, primed or designed to transform into adults after several changes.
It acts as an eating machine, gains approximately 100 times its initial body weight, and grows about 2 inches in starting weeks.
Its body has specific hormones, such as ecdysone, to perform particular tasks in its growth process. It is released throughout the larval stage and causes its skin to shed several times.
It undergoes molting more than four to five times due to the ecdysone hormone, and it also activates the imaginal discs in the later stages to form wings, legs, and antennas.
Temporary hindrance of imaginal discs
My neighbor is a professional entomologist with vast knowledge about the growth phenomenon and the steps involved in each stage.
I asked him a few questions about the larval stage and the overall process in this phase to help it transform into a butterfly.
He said the juvenile hormones hinder or restrict the imaginal discs, and these cells remain dormant in the caterpillar stage to stop the genes from turning crawling insects into adult flying species.
He further explained that the juvenile and ecdysone hormones prevented the final transformation until the caterpillar stopped feeding and the concentration of juvenile hormone declined.
Self-destruction by caspase enzymes
The final molting occurs when the caterpillar reaches the critical size and sheds the juvenile hormone with the caterpillar’s skin.
Its cell releases the caspase enzymes to dissolve and break down the tissues and its internal body organs and start chrysalis formation.
I studied in a research paper where scientists examined the caterpillar breakdown and a soup or liquid it releases to rearrange the imaginal discs.
I was surprised to learn that ecdysone hormones, known as pupa, are also released in this stage, and the nutrient soup at the base of the chrysalis helps the imaginal discs form the adult body organs.
In this phase, the juvenile hormones drop below the threshold, resulting in the caterpillar’s self-destruction and the activation of imaginal discs.
Transformation into a butterfly
The final ecdysone hormone burst causes the juvenile hormones to become zero and rearrange all imaginal discs inside the chrysalis to form an adult.
The protein-rich soup at the base of the chrysalis helps the cells and allows the genes to reshape the body and wing patterns to develop.
The cell replication occurs at a fast rate using the proteins, and a new butterfly with colorful wings, antennas, and legs appears from the chrysalis after the metamorphosis is complete.
How do you tell if a caterpillar is a butterfly or a moth?
It is not simple and easy to guess if the caterpillar will be a butterfly or a moth because they look very similar in their larval stage.
However, my colleague told me that an expert can tell you by observing the physical appearance of the caterpillar.
For example, he told me that moth caterpillars will have fuzzy bodies and furry spines on their bodies, unlike butterflies because they have tiny spikes or smoother bodies than moths.
In addition, he told me that they will have a hard outer covering known as chrysalis, while moths have silk coating. For example, you can distinguish the monarch caterpillars from their black and fatty bodies with yellow stripes.
The spicebush swallowtail caterpillars have green bodies with yellow dots and act as false eyes to scare the predators.
However, my colleague said the differences in moth species and their distinction from butterflies. He explained the wooly bear caterpillar is a moth with large orange and black spines, while the rosy maple caterpillar has a green body with black spines.
The curve-lined owlet moths have bent bodies, dull coloring, and distorted shapes in the growth stage to make them look like dried leaves, which helps them camouflage and deter predators.
How long does it take for a caterpillar to turn into a butterfly?
The time varies among species and environmental factors, such as temperature, food availability, weather, and predation.
The average time a caterpillar takes to turn into a butterfly is 15-37 days, and some species take more than 40 days to transform into an adult.
It transforms into a butterfly soon, such as within a few days if the temperature is warmer and the food availability is high.
It eats more and undergoes straight and simple metamorphosis in suitable weather conditions. However, my cousin told me that some species remain in the caterpillar stage for several months and sometimes years, especially the winter brood species.
Why does a caterpillar not transform into a butterfly or moth?
The caterpillar is the most critical stage in the metamorphosis, and the mortality rates in this stage are high.
The environmental factors and predation cause them to not turn into adults. For example, I saw a dead caterpillar in a hot summer in my yard and researched the reasons behind it because the weather changes abruptly in a few days.
I read that the temperature increases the juvenile hormones and stops the metamorphosis. Food scarcity also increases the mortality rates because they need a lot of food to feed in this phase.
In addition, I also studied that parasitic diseases and genetic defects due to interbreeding or crossbreeding cause them to die and not transform into butterflies.
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