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What is a Caterpillar Insect?

Last updated date: 15th Mar 2023
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The caterpillar insect can be defined as a larva of the moths and the butterflies. These organisms belong to the order of Lepidoptera. The Caterpillars are basically tiny insects that are voracious feeders that make them the most common pests for plants. There are so many different types of caterpillars that can vary in the sizes, colors, and diets that they have. 

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Etymology of Caterpillar Insect 

The scientific name of caterpillar is derived from the English words that include “catirpeller” and “catirpel”. These terms are in fact derived from the Older French word “Catepelose” in which the word “cat” translates to cat and the word “pelose” translates to hairy. The use of the term is to describe the moth and butterfly larvae. However, it can also be used to describe the sawfly larva in particular.

Physical Characteristics of Caterpillar Worm

Here are some of the main physical characteristics of the caterpillar larva. 

  • Caterpillars tend to have softer bodies. 

  • There may be some variations in the size of the caterpillar. They can be as small as one mm and can grow up to a size of 14 cm. 

  • Just like other insects, caterpillars have three body parts in total and those are the head, the abdomen, and the thorax. 

  • The external covering found in the bodies of the caterpillar insect is known as the exoskeleton. 

  • There are six pairs of eyes and these are known as stemmata. The arrangement of the eyes of a caterpillar is in a semicircular pattern. 

  • The eyes of a caterpillar will be able to make a differentiation between dark and light. However, these aren’t capable of detecting images. 

  • The caterpillar can move its head from one side to another in order to judge the distance and the depth of a surface. 

  • Caterpillars tend to have tiny hairs that are located all over their body and these are known as setae. 

  • The breathing process in caterpillars is facilitated with the help of tiny holes that are known as spiracles. 

  • The antennae and the setae present in the different types of caterpillar worms can help them in sensing touch. 

  • The caterpillar is able to use the three different leg pairs situated on the thoracic segments. They retain these legs when they transform into an adult. 

  • The caterpillars have more than 6 pairs of legs but most of them are false and are known as prolegs. 

  • The number of prolegs in a caterpillar can be up to 5. These prolegs have a function though. They help the caterpillar in climbing and clinging onto the plants. 

  • There are 4000 different muscles present in the soft body of the caterpillar. About 248 muscles combine together to form the head of a caterpillar.

What Do Caterpillars Eat? 

Most of the species of caterpillars are herbivorous in nature which means they only feed on plant species. However, some species tend to be insectivorous and are called cannibals. Species such as horn moths enjoy feeding on horns. Caterpillars tend to feed mostly on agricultural lands and hence are considered notorious pests for agriculture. The moth caterpillar in particular causes a lot of damage to agriculture products. It is really important for the caterpillars to consume a lot of food so that they can sustain the process of growth and move on to the later stage that is adulthood. The caterpillars that are malnourished don’t really get to properly transition into adulthood. Even if they reach the stage, they will have difficulty in producing eggs and sometimes aren’t able to do so at all. In their entire lifetime, caterpillars consume about 27000 times their entire body weight.

The Process of Growth In A Caterpillar Worm 

Just within a span of a few weeks, caterpillars are able to grow at an exponential rate. These organisms molt several times as these tend to grow bigger and hence have an increase in their weight. There is a specific term used to describe the particular stage between these molts and it is known as an instar. Most caterpillars tend to have about six instars in total before they turn into a pupa.


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Interesting Facts About Caterpillars 

  • The entire lifespan of a caterpillar is about 2-4 weeks in total. 

  • The most popularly known caterpillar is situated in North America and it is known as the Monarch butterfly caterpillar. 

  • Most of the species of caterpillars have a nocturnal nature. 

  • After an egg of a caterpillar is hatched, it will consume the remains of the shell. The outer layer of the eggshell that is consumed by the caterpillar is known as chorion. 

  • The caterpillars move in a motion that resembles a wave.

  • Most of the host plants that are targeted by caterpillars tend to produce certain toxic compounds so that these herbivores are discouraged from consuming the plants.


Caterpillars are defined as the larvae of butterflies and moths. The scientific name of caterpillar depends on the species that it belongs to. These organisms tend to have a lot of muscles in their body which are soft to touch. Some species of caterpillars have a very important role to play in the production of silk.

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FAQs on Caterpillar Insect

1. Do caterpillars produce silk? 

Some species of caterpillars tend to produce silk. They are able to do so with the use of their salivary glands that are situated along the side of their mouth. An example of such a species is the Eastern Tent Caterpillar. The name of this insect comes from the silk tent that it creates for shelter. The Gypsy moth caterpillars also construct a particular silken thread that they used in order to create balloon-like structures around the treetops. The caterpillars also use this silk that they produce when they move to the stage of becoming pupae. The caterpillars build a cocoon around the pupae with the help of the silk that is produced.

2. Explain the properties of Self-Defense in caterpillars.

The caterpillar insect has a very high amount of protein constituents in its body. This makes them common prey for bigger animals and insects. Hence, there are certain self-defense tactics that caterpillars use in order to protect themselves from such creatures. One of the most common self-defense tactics used by the caterpillars is thanatosis which is also called ‘playing dead’. Some other caterpillar species tend to use the method of mimicry for defending themselves. The black swallowtail is a caterpillar that mimics the shape of bird droppings and inchworms tend to take the shape and looks of twigs. Some of the other caterpillars also turn themselves into a brighter color so that they can appear toxic to the predators.

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