10 Incredible Caterpillar Facts

Written by Emmanuel Kingsley
Updated: July 28, 2022
Image Credit Jay Ondreicka/Shutterstock.com
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The caterpillar is an insect in the larva stage of members of the Order Lepidoptera. It comes from a long line of multi-varied families and has a global presence with locations including Asia, Africa, Central America, South America, Eurasia, Oceania, Europe, and North America.

There are plenty of interesting things about caterpillars that you probably didn’t know before. Below are 10 incredible facts about caterpillars.

1. Caterpillars Spend Much Of Their Time Eating

Cactus moth caterpillar on a prickly pear cactus
Without proper nutrition, sole caterpillars may not successfully complete their metamorphosis.

Catherine Eckert/Shutterstock.com

As we mentioned earlier, caterpillars are in the larval stage of moths and butterflies, which means they are not fully developed. It appears that an integral (if not the most integral) part of their development process is eating. Some scientists believe that they eat as much as 27,000 times their actual body size.

Their first meal is set as soon as they get out of their shells, and it is the very proteinous egg shells. Without proper nutrition, sole caterpillars may not successfully complete their metamorphosis. Some malnourished caterpillars may make it out, but their fertility would typically be affected, as they might not be able to produce enough eggs.

So, if you were already judging them for being gluttonous, you might want to take that back. Eating that much is their way of surviving long enough to complete their metamorphosis.

2. A Caterpillar Has Up To 4,000 Muscles

A single caterpillar often has up to 4,000 muscles in its body. If you’re not very impressed, let’s put it in perspective. Human beings have just about 650 muscles. That would mean caterpillars have about six times as many muscles as we do.

Their head capsules alone have 248 different muscles, and each body segment is controlled by up to 70 muscles. It is also interesting that every single one of the 4,000 muscles has at least one neuron supplying them with nerves.

The question then begs, “why would they need these many muscles?”  The answer to that is simple – they need the muscles to help with their wave-like movements.

3. Caterpillars Have Only Six True Legs, And Their Movements Are Wave-Like

The Hawk Moth caterpillar’s back legs, which are formally called anal prolegs, are flattened so they can hold on tightly to the plant as the caterpillar feeds.
Caterpillars have no more than six true legs, even though it might appear like they have more.

Chekaramit/Shutterstock.com

Regarding movements, caterpillars have no more than six true legs, even though it might appear like they have more. The other legs are not actually legs; they are called pro legs, and they are meant to help a caterpillar make its way through plant surfaces. The prolegs may number up to 10, and they have some small hooks that help them hold on to the surfaces without slipping and falling.

Also, thanks to these pro legs, you can totally predict their movements. After anchoring themselves with pro legs, caterpillars would move forward with one pair of legs at a time, starting with the rear legs. This makes their movement wave-like and undulating.

However, their unusual locomotion involves more than just leg movements; many things go on during movement, including changes in blood pressure.

4. Caterpillars Can Turn Around Toxins In Host Plants For Their Good

A lot goes down in the world of plants and caterpillars, even as they jointly evolve. Some host plants produce certain toxins to turn off herbivorous animals, including caterpillars. While this strategy works on many herbivores, some caterpillars have found a way of making this work out for them too.

What they do is to get some of these toxic compounds into their bodies so as to protect themselves from their predators. For instance, the monarch caterpillar sequesters toxic glycosides from the milkweed plant as a way of making itself grossly unpalatable to birds and other caterpillar-eating predators.

5. Caterpillars Can Mimic Snakes

Snakes are among the most feared creatures in the wild, and caterpillars sometimes mimic them. In a bid to deter predators, caterpillars would sometimes mimic snakes by retracting their legs and expanding their anterior body segments, which effectively gives them a snake look.

This mimicry is mostly employed by hawk moth caterpillars, especially the Hemeroplanes triptolemus. The resemblance of this mimicry is so uncanny that it fools not only predators but also humans.

However, the Hemeroplanes triptolemus is only found in Guatemala, Belize, and Costa Rica.

6. Caterpillars Have Twelve Eyes

Close up of the giant leopard moth caterpillar
Caterpillars have about a dozen eyes.

iStock.com/Eblis

Another fascinating fact about caterpillars is that they have about a dozen eyes. On either side of a caterpillar’s head are 6 tiny eyelets known as stemmata. Some other species have 5 or 7 on each side.

One would expect that a creature with 12 eyes would enjoy incredibly excellent vision. Well, not so. The eyelets only help them distinguish light and dark. However, when it comes to identifying colors or just seeing stuff, caterpillars are naturally handicapped.

7. Some Caterpillars Can Kill Humans

Did you know that some caterpillars can develop poisons that could kill humans? That’s a shocking twist in their cute story, but it is true. Various caterpillar species can do this, with some being more proficient than others.

A prime example of a lethal caterpillar is the giant silkworm moth caterpillar. Also known as the assassin caterpillar, it is responsible for many human deaths in Brazil and South Africa. A single contact with this caterpillar can cause many symptoms, including vomiting, severe abdominal pains, and total kidney failure. This caterpillar is the type to look out for and avoid contact with.

Other caterpillars may not necessarily kill but can hurt humans. They include saddleback caterpillars, cinnabar moth caterpillars, and puss caterpillars, amongst others.

8. Caterpillars Do Not Have Lungs

Lungs are the major respiratory organ in most animals, including human beings. However, caterpillars are among the few creatures that exist without lungs. However, they have spiracles located on different parts of their bodies, which are all connected to the trachea. Much of the respiratory activity in caterpillars occurs during movements.

9. Caterpillars Produce Silk

The Cecropia moth caterpillar feeding, and showing distinctive warning coloration on a plant in a Wisconsin butterfly exhibit. The caterpillar's body is full of bristles.
Some caterpillars can produce silk through an opening on their lips known as a spinneret.

K Hanley CHDPhoto/Shutterstock.com

Some caterpillars can produce silk through an opening on their lips known as a spinneret. The spinneret produces liquid silk, which becomes solid silk after contact with air. While some can make habitable tents out of the silk, others only make silk once in their lifetime to create a cocoon (a protective case crucial to their metamorphosis).

It is important to note that butterfly caterpillars do not make cocoons, and cocoon creation is exclusive to moth caterpillars.

10. Caterpillars Retain Some Of Their Memories As Caterpillars Even After Metamorphosis

The morphing process of most caterpillars often involves a complete dissolution into a liquid substance, which makes it seem like they are becoming something entirely new. However, research shows that caterpillars retain some of the things they learn, even after becoming moths and butterflies. They don’t retain all of their memories, though; just those of biological importance.

Black Swallowtail Caterpillar (Papilio polyxenes)
Black Swallowtail Caterpillar (Papilio polyxenes)
Jay Ondreicka/Shutterstock.com
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