How Long Does It Take Caterpillars to Turn into Butterflies?

The length of time it takes a caterpillar to turn into a butterfly depends on the butterfly species, host plant type, food availability, habitat threats, and weather conditions, but it can take between 5 days and several months.

Short Overview of a butterfly’s life cycle

Butterflies undergo complete metamorphosis, unlike other types of insects like grasshoppers and crickets. Four stages of the butterfly life cycle are:

  • Egg
  • Larva (caterpillar)
  • Pupa (chrysalis)
  • Adult butterfly (imago)

How Long Do Caterpillars Stay as a Caterpillar For?

Monarch caterpillar
Monarch caterpillar

The length of time a caterpillar stays a caterpillar, and the number of instars varies for different butterfly species. However, note that all caterpillars molt multiple times, regardless of the species. This happens because their exoskeletons don’t stretch as they grow.

Environmental aspects greatly impact the larval stage duration. A list of conditions that can affect it includes:

  • Temperature
  • Time of year
  • Type of host plant
  • Scarcity of food
  • Predators
  • Parasites
  • Diseases

Due to all these circumstances, caterpillar mortality rates are high, and many do not make it to the chrysalis stage. However, caterpillars can be adaptable, particularly to hot and cold temperatures, and can stay dormant for extended periods. During winter, they can enter diapause, a hibernation-like state. The caterpillar stage can take anywhere from 5 days to several months.

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The Caterpillar stage is also called the feeding stage

This stage is also known as the feeding stage. Once a caterpillar hatches from the egg, it may eat its eggshell. It then continues to feed on the host plant leaves to increase its body mass in preparation for the pupa stage. That’s why food availability is crucial in caterpillar survival.

Caterpillar size examples

Depending on the species of butterflies, the size of caterpillars can vary from 0.039 inches (one millimeter) to 5.5 inches (14 centimeters).

For instance, a Painted lady caterpillar grows to about 1.25 inches (3.17 cm), while a Black swallowtail butterfly caterpillar can reach up to 2 inches (5 cm).

Similarly, a Monarch caterpillar is usually about 2 inches (5 cm) long at the end of the caterpillar stage, and it grows up to 100 times in size. The Monarch butterfly caterpillar is a perfect example of distinctive rapid growth in butterfly caterpillars.

Initiating a Cocoon


Juvenile hormone (Neotenin) controls the metamorphosis in the butterfly larval stage. When the juvenile hormone level lowers, and the caterpillar outgrows its skin, it triggers cocoon initiation instead of molting further. It sheds its skin for the last time and builds a chrysalis from its outer coating, usually hanging upside down.

A chrysalis has a hard exterior and blends into the surroundings as a protection mechanism. It encloses caterpillars, so they don’t eat when they pupate. They use the energy they accumulated in the larval stage.

Forming a pupa

The forming pupa releases enzymes (caspases) that dissolve most old, non-vital tissues by turning them into a fluid and building a new body in the chrysalis. Caterpillars already have internal organs and eyes, as well as short legs and small antennae. Imaginal discs (disc-shaped groups of cells) stay dormant in the larval stage.

Once a caterpillar turns into a pupa, imaginal discs start growing and form adult butterfly body parts – wings, long antennae and legs, genitals, and proboscis (a tubular mouthpart that adult butterflies use to drink nectar). Imaginal discs are known for rapid cell division and can increase the cells up to 1,000 times during the pupa stage.

How Long Do Caterpillars Stay in a Cocoon?

Most caterpillars stay in the cocoon from 5 to 21 days, but it can take even up to 3 years if the conditions are harsh. This can happen in deserts, but it’s rare. Usually, diapause over winter delays the final stage for up to a couple of months. Therefore, the environment affects the duration of the pupa stage the most.

Final moment – Emerging as a Butterfly

The emerging process is called eclosion. It includes splitting the pupal case and drying, straitening, and strengthening the folded, wet wings by pumping blood into them. This can take a few hours. When the butterfly’s wings are completely expanded, it’s ready to fly, mate, and lay eggs, starting the life cycle over.

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