Difference between Worm and Caterpillar

At first, worms and caterpillars might look similar to each other. They both are small and move in a twisting or snake-like fashion. Some even confuse these two, by often referring to caterpillars as worms. However, they are entirely different kinds of animals.

What are Worms?

Worms are a type of crawling animal or reptile that can be of any kind or size, as a serpent, caterpillar, or snail. It has no feet or very short ones. They are invertebrate animals with soft, slender and elongated bodies. They lack brains, eyes, and nerves. They live in different and often hostile environments.

Many consider worms as insects, however it is not true. Insects have exoskeletons that provide a skeletal support and protect their internal organs, unlike worms.

Worms help soil keep loose and absorb more water and nutrients. They lack lungs, and breathe through skin. Most of the worms are less than 1 cm in length, while the longest ones can reach massive lengths of 50 m.

What are Caterpillars?

Caterpillars are the larva (immature form) of a flying insect, commonly a butterfly. It is the second stage in the life cycle of egg, larva, pupa and adult. They are often seen as pests by gardeners and farmers. They generally feed on plants.

There are two types of caterpillars − generalist feeders and specialist feeders. The former eats a variety of plants, while the latter are carnivores and feed on insects. They live in a habitat with lots of plants, trees and flowers. Some natural predators of caterpillars include wasps, birds and parasites.

Similarities between Worms and Caterpillars

Both worms and caterpillars are invertebrates, have soft bodies, are cold-blooded, have defense mechanisms to fight predators, and take benefit of the ecosystem. Some types of worms and caterpillars act as a good source of protein. Both are prodigious feeders of verdure.

Difference between Worms and Caterpillars

The following table highlights the major differences between Worms and Caterpillars −





These are different and distant-related animals with a long cylindrical tube-like body without limbs and eyes.

These are the larval stage of a member of the Lepidoptera, the insect order comprising of moths and butterflies.


Some worms live and thrive in the bodies of animal and human hosts.

These are pests living outside of the host.

Feeding parts

They lack complex chewing parts.

They have strong, well-developed jaws that have sharp cutting surfaces used to chewing.


They lack eyes.

They have about six pairs of eyes, ocelli to detect changes in the intensity of light but do not form images.


They do not have limbs and move using their long or circular muscles.

They have around five or six pairs of prolegs that enable movement. Abdominal muscles enable forward movement.

Life cycle stages

This the adult stage of the development life cycle.

This the second stage of the development life cycle.


They are parasitic and mostly live in their host’s bodies. Some live free in the marine environment. Some live underground by burrowing.

Their natural habitat are plants and vegetation.


These are often used to decay agricultural waste and for useful management. They fall into the invertebrate species of insects.

Some people eat caterpillars as food.


Their primary purpose is to create air in soil for better circulation of air and water.

The purpose of caterpillar is to eat leaves and get bigger to turn.

The major difference between worms and caterpillars is that the latter have different sizes and different characteristics. Caterpillar is much smaller as compared to a worm. A worm can grow up to 15 cm while caterpillar does not even grow to even half of it.

Worms are quite tough to find than caterpillars. Worms are rather healthy and comfortable while living in moist areas. Caterpillars can easily be spotted in plant leaves or green leaves but worms cannot be seen easily. Worms rather stay underground and stay wet.

Worms are less harmless than caterpillars. Caterpillars can spoil trees and plants very quickly. Worms are afraid of humans and large insects; thus, they stay safe under the soil. Worms do not spoil or destroy unlike caterpillars.

Caterpillars cause huge loss to farmers who have good number of crops for agriculture. On the other hand, worms help soil suck air as well as increase fertility of soil.

Worms make a good fertile for all types of soil. Caterpillars do not have such qualities which can profit soil or plants.


Some caterpillars and worm species are parasites or diseases, while others have many environmental benefits. Caterpillars further develop into Lepidoptera which helps fertilize plants and produce seeds for animals and humans to eat. Caterpillars are must for native wildlife pollination. They are particular creatures and do not prefer invading or imported plants.

Worms may not seem a nice thing at first, but they actually very helpful. It is also believed that they are the key to the future. They are also a good source of protein and contribute a lot to sustainable gardening. Some caterpillars can develop poisons that can even kill humans. For example, giant silkworm moth caterpillar. It is responsible for many human deaths in Brazil and South Africa.