Who Preys on Woolly Bear Caterpillars? Their Predators and Defense Mechanisms

What are the woolly bear caterpillar predators in the wild, and how do they protect themselves from these hunters? Read on to learn about the fascinating defense mechanisms of these tiny creatures

Tiny caterpillars are easy prey for hunters in the wild. This happens because they are easily accessible and full of protein.

But these tiny caterpillars have evolved a defense system of their own that helps them to steer clear from the dangers of the wild.

In this article, we will talk about the woolly bear caterpillars, what hunts them, and how they protect themselves from such dangers.

What Are Wooly Bear Caterpillar?

The woolly bear caterpillar is the larval form of tiger moths. there are several species of Tiger moths, such as Giant Leopard moths, Isabella tiger moths, Eastern Tiger moths, and so on. 

These worms are known for the thick coat of bristle-like hair on them. In fact, there is a myth surrounding their hair that says that one can predict the upcoming winter by looking at them!

They have a black-colored body with a rustic brown band in the middle. However, the color of the body keeps changing with age and the feeding capacity of these insects in the caterpillar form.

The woolly bears can be found across different parts of North America, Mexico, and Southern Canada. Being herbivorous in nature, they actively eat leaves from small plants and leaves of elm, maple, and more.

Who Eats Them?

One of the main predators of woolly bears is birds that hunt hairy caterpillars.

Brown thrashers, American crows, and rufous towhees are some of the ideal examples of birds that prey on woolly bear caterpillars.

Apart from birds, they are also hunted down by mammals like raccoons, red foxes, deer mice, coyotes, and other larger mammals.

Insects like parasitic wasps (such as yellow jacket wasps) and flies are also dangerous for them.

Since they have a lot of predators, woolly bears have their own defense mechanism to protect themselves.

Wooly Bear Caterpillar Defense Mechanisms

Woolly bears usually curl up like a ball and play dead whenever they feel threatened. They lie motionless (or rather play dead) in this position until the threat has passed.

There are other techniques and traits that these insects use to keep themselves protected against the cold and predators. Let us look at them in detail in the sections below.

Surviving Extreme Cold

Usually, it is tough for caterpillars to survive the extremely cold winters, but the woolly bears can survive in temperatures that go way lower than the 0 degrees F.

During such times, they produce a substance in their body called glycerol. Glycerol prevents the inner body parts from getting frozen.

Thus the caterpillar slowly freezes during the winter, but they still remain alive as its internal organs are intact and working correctly.

They can survive temperatures that are as low as -90 degrees F. At times, they survive the winter inside an ice cube. Fascinating, isn’t it?

They also search for warmer places, like crevices in the rocks, abandoned logs, etc., to hibernate throughout the cold season. Thus they can easily survive tough to mild winters.

Bristles To Defend Against Large Predators

The stiff hairs or bristles on the body of these caterpillars are extremely important to save them from larger predators like raccoons and red foxes.

As mentioned above, these worms curl up like a ball when they sense danger. When they curl up, the bristles get pointed outside and provide protection to the internal organs of the body.

Since these bristles are dangerous for insects like wasps, they usually refrain from attacking.

When it comes to larger predators, if they try to swallow the caterpillar, the bristles will get stuck in the throat, causing gagging, coughing, and irritation.

This is also one of the main reasons why you should keep pets like dogs and cats away from the woolly bear caterpillars.

Self-Medication Against Parasitic Larvae

Apart from the large predators, there are some parasites that attack these worms from the inside.

To deal with such predators, they have developed a unique “self-medication” technique.

When parasitic flies lay eggs on these caterpillars, they start consuming plants with bitter compounds, which keeps the parasitic larvae away from them.

Interestingly, the caterpillars don’t normally consume these plants as they contain pyrrolizidine alkaloids which can affect their growth. They only do it when faced with parasites.

What Do They Eat?

Wooly bears are herbivores, and they mainly feed on plants, herbs, leaves, and more. They usually like to eat herbaceous plants that are low-growing and bear seeds.

Usually, they prefer eating fallen leaves rather than grass or plants. Clovers, curly dock, and dandelions are some of their favorites.

They also eat leafy vegetables like spinach, cabbage, and more. If there are no fresh leaves to consume, they will consider eating blades of grass, maize, barley, and more.

Frequently Asked Questions

Wrap Up

Being small worms, the woolly bears fall at the bottom of the food chain, but despite this, it is fascinating to see the tiny tricks they use to keep themselves safe from predators and the weather.

We hope that you found the article informative and it answered your questions as much as possible. The unique defense mechanisms of these bugs make them even more interesting than the legends and myths that surround them

Thank you for reading!