is a caterpillar an insect

Perhaps you have come across one of the more than 180,000 different types of caterpillars that exist and are wondering if they are insects!

So, Is a Caterpillar an Insect?

Well, the answer to the question “is a caterpillar an insect” is yes, a caterpillar is an insect, but it is not a type of bug. A caterpillar falls into the insect category because it has an exoskeleton, three sets of true legs, a set of antennae, and a segmented body with three main parts.

In this article, apart from answering your question “is a caterpillar an insect”, I share 10 amazing facts about caterpillars that you do not know!

Are you ready? Let’s dig in!

Read also: 6 Most Common Caterpillars in Florida

6 Amazing Facts About Caterpillars

I guess you have seen a caterpillar in your lifetime, and you have probably even handled one. But how much do you know about them? 

These amazing facts about caterpillars will renew your respect for what amazing creatures they are!

Read also: Top 10 Common Caterpillars in Texas

1. Caterpillars Have 12 Eyes

A caterpillar has 6 tiny eyelets on each side of its head. These eyelets are called stemmata – and they are arranged in a semi-circle.

One of the 6 eyelets is normally offset a bit and positioned closer to the antennae.

You may think having multiple eyes would help the caterpillar have supervision – but this is far from the reality.

The tiny eyelets serve to help the caterpillar differentiate between dark and light. If you observe a caterpillar, you will notice it sometimes moves its head from side to side.

This helps it judge distance and depth as it navigates somewhat blindly.

2. Caterpillars Produce Silk

Caterpillars can produce silk using modified salivary glands along the sides of their mouth.

A few caterpillars such as gypsy moths disperse by “ballooning” from the treetops on a silken thread. Others, such as webforms or eastern tent caterpillars construct silk tents in which they live communally.

Bagworms use silk to join dead foliage together into a shelter. 

Additionally, caterpillars can use silk when they pupate either to construct a cocoon or suspend a chrysalis.

Read also: Ultimate Guide on How to Care for Echeveria Miranda

3. Caterpillars Move in a Wavelike Motion

Caterpillars with a full complement of prolegs move in a predictable motion.

Normally, the caterpillar will first anchor itself using the terminal pair of prolegs and then reach forward with one pair of legs at a time, beginning from the hind end.

However, there is more going on than just the leg action.

As the caterpillar moves forward, its blood pressure changes, and its gut, a cylinder suspended inside its body, advances in sync with the head and rear end.

Loopers and Inchworms, which have fewer prolegs, move by pulling their hind ends forward in contact with the thorax and then extending their front half.

4. Caterpillars Have 6 Legs

Perhaps, most of the caterpillars you have seen have more than 6 legs. However, most of those legs are false legs referred to as prolegs. These help the caterpillar hold onto plant surfaces and allow it to climb. 

The six legs on the caterpillar’s thoracic segments are the true legs, which it will retain into adulthood.

A caterpillar may have up to 5 pairs of prolegs on its abdominal segments, normally including a terminal pair on the hind end.

5. Caterpillars Have Creative Self-Defense Mechanism

Life at the base of the food chain can be difficult. 

As such, caterpillars employ all kinds of strategies to avoid being fed on by birds.

Some caterpillars, like the early instars of black swallowtails, resemble bird droppings. 

Certain inchworms mimic twigs and bear markings that resemble leaf scars or bark.

Other caterpillars employ a totally different strategy – they make themselves visible with bright colors to advertise their toxicity. 

Several caterpillars, such as the spicebush swallowtail, display their large eyespots to deter birds from eating them. 

If you have ever tried to pick a caterpillar from its host plant only to have it fall to the ground, you have noticed it using thanatosis to thwart your efforts of collecting it.

A swallowtail caterpillar can be identified by its smelly osmeterium, a special defensive stink gland just being its head.

6. Caterpillars Get More Than Food From Their Host Plant

Most caterpillars use the toxins from their host plants to their own advantage.

Caterpillars and plants know how to co-evolve.

A few host plants produce toxic or foul-tasting compounds meant to dissuade herbivores from feeding on their foliage. However, most caterpillars can sequester the toxins in their bodies, effectively using these compounds to protect themselves from predators.

A good example of this is the monarch caterpillar and its host plant, milkweed. 

The monarch caterpillar feeds on glycosides produced by the milkweed plant. These toxins are retained within the monarch through adulthood, making the butterfly unpalatable to birds and other predators.

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