Monarch Butterfly Caterpillars: Everything You Need to Know

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key point

  • The monarch butterfly larvae (the stage before the monarch butterfly) feed on milkweed and store toxins. These toxins can be harmful to humans.
  • Monarch butterflies are long-distance migrators and can migrate great distances.
  • They are very unique and widely recognized due to their color.

Humans have been fascinated by monarch butterflies and monarch butterflies for centuries. Not only are these milkweed butterflies beautiful in bright orange and black, but they also undergo an exceptionally arduous and fascinating migration that can take generations to complete.

That means a butterfly from New York could start its journey to Mexico, even though its great-great-great-grandchildren might end up arriving.

Another amazing fact about this butterfly is that its larva, caterpillar and its chrysalis are all beautiful – something that most butterflies don't. Emperor caterpillars are also completely harmless, with no barbed spines or hairs, and they are often bred until they complete the metamorphosis stage.

Monarch butterflies have the same life cycle as all other butterflies and many other insects. It undergoes complete metamorphosis, which means it starts as a larva, becomes a pupa, and then emerges from the pupa to become an adult animal that looks completely different from the larva.

Here are some facts about the emperor caterpillar.

Monarch Butterfly Caterpillar Everything You Need To Know 1
The monarch butterfly caterpillar has beautiful black, yellow and white stripes on its body.


How to Identify Monarch Caterpillars

Identifying adult monarch butterflies is easy. Even someone who knows a thing or two about caterpillars can recognize the monarch caterpillar of the monarch butterfly. It is a medium-sized, plump caterpillar with white, black and yellow stripes that give it a distinctive look. Even the caterpillars of its cousin, the queen butterfly, which are similarly colored but patterned differently, cannot be mistaken for it.

Like most caterpillars, it goes through several stages before it is ready to pupate. These stages in the caterpillar life cycle are called instars.

The first instar hatches from eggs. Identifying the larva at this stage can be tricky because it doesn't look like the prototype monarch butterfly caterpillar. It is glossy, translucent pale green with a black head, not the diagnostic black, yellow, and white.

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It eats the remaining eggs first, and then starts eating the host plant, which is almost always milkweed. It measures between 0.08 and 0.24 inches.

Streaks only appear when the first instar molts. There is also a yellow triangle on the head surrounded by yellow stripes. The caterpillar's two pairs of tentacles, one on the thorax and one on the abdomen, begin to grow. This caterpillar measures between 0.24 and 0.39 inches.

After the third molt, the tentacles become longer. Biologists consider these tentacles to be sensory organs, although caterpillars do have tiny antennae. The stripes or bands are more pronounced, and the caterpillars are between 0.39 and 0.59 inches in length. A fourth-year-old monarch has developed white spots on its back and is now between 0.59 and 0.98 inches in size.

Wuling's ribbon is more complicated, with tiny front legs growing near the head. Caterpillars feed on milkweed and can grow up to 1.96 inches long. When it reaches its maximum size, the caterpillar stops eating and starts looking for a place to pupate and continue its life cycle.

Where are they usually found?

The scientific name of the monarch butterfly is Danaus plexippus , which is distributed in North America. Its habitat includes clearings, roadsides, wet meadows, gardens, swamps, pastures, and clearings. In other words, it shares the same habitat as milkweed plants.

Monarch butterfly caterpillars feed on milkweed.

© Keifer

Five Cool Facts About Monarch Butterfly Caterpillars

Viceroy versus Monarch
A monarch butterfly sits on an orange cosmos in spring.


The monarch butterfly caterpillar is a fascinating creature known for its unique appearance and interesting behavior.

Here are five cool facts about these amazing creatures:

  1. Monarch butterfly caterpillars are instantly recognizable due to their distinctive black, white and yellow stripes. It also has rows of black spots on its body that are thought to help protect it from predators.
  2. Monarch butterfly caterpillars are voracious eaters and can consume up to 200 times their body weight in milkweed leaves during their development. This diet provides them with the toxic chemicals they need to protect themselves from predators.
  3. As monarch butterfly caterpillars grow, they go through a process called molting, which involves shedding their skin. They do this multiple times during development, each time growing bigger and shedding their old skin.
  4. Monarch butterfly caterpillars have a unique way of protecting themselves from predators. They mimic the appearance of the poisonous milkweed plants that feed on them, making them less attractive to predators that have learned to avoid the poisonous plants.
  5. When monarch butterfly caterpillars are ready to pupate, they produce a silk thread and attach themselves to a leaf or stem. They then spun a silk mat, hanging it upside down in a "J" shape for a few hours before turning it into a silkworm chrysalis.
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All in all, the monarch butterfly caterpillar is a fascinating creature with many unique adaptations and behaviors.

what do they eat

Monarch butterflies eat only milkweed, so much so that they and their cousins are known as milkweed butterflies. The life cycle of a butterfly begins with the female carefully laying her eggs, one at a time, on the leaves of a plant, securing them with a bit of natural glue.

Beyond that, she does not provide any parental care. Over the course of about a month, she can lay as many as 500 eggs. When the caterpillar hatches, it first eats the egg shell and then starts eating the leaves.

The leaves of the milkweed plant are poisonous to many animals, but the monarch butterfly caterpillar can store the toxins in its body, and the toxins are still there when it breaks out of its cocoon and emerges as a butterfly. The bright colors of the butterfly warn potential predators that it is poisonous.

how to raise them

Raising a monarch is easy and fun. Not only that, but it also benefits butterflies whose conservation status is close to being threatened. They've even been successfully grown up on the International Space Station.

The first thing to do is to grow some milkweed in the garden, or find a reliable stand outdoors. Then, buy two containers. They don't have to be huge, but the first one needs to be big enough to hold the eggs as well as the first and second instars.

The second needs to be large enough to hold the mature caterpillar, its pupa and adults. Check milkweed plants for eggs during their growing season. If there is egg on the leaf, just cut off the leaf and put it in. You don't need to touch the monarch butterfly caterpillar at all during your care.

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Line the first container with paper towels, spray it with water, and place the leaves on top. Close the top of the container and place it in bright light, but not in full sun. Make sure to keep each container clean, including removing soiled paper towels, and feed the caterpillars milkweed leaves daily. When the caterpillar is ready to pupate, it moves to the top of the container.

It attaches itself there, hangs in a J-shape for half a day, and then splits its skin to reveal a pupa.

Identification of monarch chrysalis is also easy. It is a beautiful light green with gold accents on the top and bottom. It hangs for about two weeks and then becomes transparent before the butterflies emerge.

It takes three to four hours for the insect's wings to harden, and the container should be large enough for it to flap its wings by then. After that, it can be released. Butterflies can spend the night in flight cages if the weather is inclement.

One caveat about breeding monarch butterflies is that the adults don't seem to migrate as successfully as wild butterflies.

Emperor caterpillars take about three to eight days to hatch.

© Keifer

How long do they hatch?

Monarch butterfly eggs take about three to eight days to hatch. Emperor caterpillars take less than a month to pupate. Pupation takes approximately 8 to 15 days.

When does breeding and hatching season usually occur?

Breeding and hatching of monarch butterflies usually take place in spring and summer. The first monarchs emerge in April, and four days later they begin mating and laying eggs. They begin their journey north, laying eggs en route to the northern United States and southern Canada.

The eggs hatch four days after laying. For the next two weeks, the larvae feed on milkweed before turning into pupae.

Four generations of monarch butterflies are born each year. The first three generations have a relatively short lifespan, lasting about two to six weeks, however, the fourth generation of monarch butterflies migrates to warmer climates and survives for about eight months until spring.


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