What Do Mourning Cloak Caterpillars Eat: A Quick Guide for Curious Minds

Mourning cloak caterpillars are a fascinating and unique group of insects. They’re known for their spiny appearance and their eventual metamorphosis into the elegant mourning cloak butterfly. If you’re interested in learning more about these fascinating creatures, understanding their diet is an essential aspect to explore.

These beautiful caterpillars are not very picky eaters, which makes them quite adaptable in various habitats. They love to feast on the leaves of trees like elms, willows, and poplars [1]. Sometimes, you may even find them munching away happily on other deciduous trees or shrubs in groups, consuming one branch before moving on to the next1.

As you delve deeper into the world of mourning cloak caterpillars and their dietary preferences, it is essential to remember that their feeding habits play a critical role in their development and survival. So, be sure to keep an eye out for these intriguing insects and appreciate the wonder of nature they represent.

Biology of Mourning Cloak Caterpillars

Mourning Cloak caterpillars, or Nymphalis antiopa, are quite fascinating. They are known for their spiny appearance and relatively large size. In their larval stage, these caterpillars have a voracious appetite, feeding primarily on the leaves of elm, willow, and other deciduous trees. Let’s take a closer look at their biology and life cycle.

Life Cycle of Mourning Cloak Caterpillars:

  • Egg stage: The female butterfly lays her eggs in clusters on the undersides of leaves.
  • Larva stage: After hatching, the caterpillars feed together in groups, moving from branch to branch as they defoliate it.
  • Pupa stage: The caterpillars form a chrysalis and transform into butterflies.
  • Adult stage: The Mourning Cloak butterflies emerge, take flight, and mate to start the cycle anew.

When it comes to size, Mourning Cloak caterpillars can grow quite large and look somewhat intimidating with their spines. However, you don’t need to worry, as they are completely harmless.

As the caterpillars consume leaves during their larval stage, they offer benefits to the ecosystem. They provide a crucial source of food for various predators, such as birds and small mammals.

To put things in perspective, here’s a quick comparison table of Mourning Cloak caterpillars and other common caterpillars:

Caterpillar Type Size Appearance
Mourning Cloak Relatively large Spiny, black & white
Monarch Medium-sized Black, white, & gold
Eastern Swallowtail Medium to large Green or brown
Hickory Horned Devil Very large Green, spiky horns

Ultimately, understanding the biology, behavior, and life cycle of Mourning Cloak caterpillars helps you better appreciate their role in nature and their unique characteristics.

Remember to keep an eye out for these fascinating creatures while exploring the outdoors, as they’re sure to spark your curiosity and wonder.

Diet of Mourning Cloak Caterpillars

Mourning cloak caterpillars, also known as spiny elm caterpillars, have a particular diet that mainly consists of the leaves from various trees. Let’s explore their preferred food sources in more detail.

Preferred Trees:

  • Willows
  • Elms
  • Hackberries
  • Cottonwoods
  • Birches
  • Poplars

These caterpillars enjoy the foliage of these trees, particularly the leaves of the American elm, but will also consume other parts of the tree like tree sap and bark when available. However, their preference could vary depending on the geographical location and tree species availability.

For example, in the Northeast part of North America, they might primarily feed on willows and American elms, while in the West, they may favor cottonwoods and poplars. Remember that their diet impacts their growth and ultimately their transformation into mourning cloak butterflies, so providing a variety of suitable host trees will support their development.

When it comes to finding food, mourning cloak caterpillars tend to feed in groups, usually defoliating one branch before moving on to the next. This communal feeding behavior helps them quickly consume the foliage of their preferred trees, ensuring they receive the necessary nutrients for their growth and development.

In conclusion, mourning cloak caterpillars have a specific diet focused on the leaves of various trees. By understanding their preferences, you can better appreciate these fascinating creatures and perhaps even contribute to supporting their existence in your local environment.

Types of Host Plants

Mourning cloak caterpillars are known to feed on the leaves of various deciduous trees and shrubs. Some common host plants include:

  • Willow
  • Elm
  • Cottonwood
  • Aspen
  • Birch
  • Hackberry

These caterpillars prefer the leaves of these trees due to their nutritional content and availability throughout their habitat.

You might wonder if mourning cloak caterpillars feed on other types of plants, such as roses. While they seem to primarily feed on the leaves of deciduous trees mentioned above, there is no strong evidence to suggest that these caterpillars commonly feed on rose plants.

By familiarizing yourself with these host plants, you can better understand the preferred habitat and feeding habits of the mourning cloak caterpillar.

Life Cycle and Reproduction

Mourning cloak caterpillars, also known as spiny elm caterpillars, are the immature stages of the Nymphalis antiopa or mourning cloak butterfly. They are quite fascinating creatures, and in this section, you’ll learn briefly about their life cycle and reproduction.


Your journey begins with the mourning cloak butterfly laying clusters of eggs, usually on leaves of their preferred host plants such as elm, willow, and birch. These eggs hatch into larvae, which will grow and develop into the spiny caterpillars.


As a spiny elm caterpillar, you’ll initially live and feed communally in groups with your siblings, defoliating one branch before moving on to the next one. As you grow, you’ll shed your skin multiple times throughout your development (these stages are called instars).


When you’ve reached your full size as a caterpillar, it’s time to form a pupa or chrysalis. Here, you’ll undergo a remarkable transformation called metamorphosis. A whole new world awaits you as an adult butterfly.


Congratulations! You’ve emerged as a beautiful mourning cloak butterfly, adorned with maroon-brown wings, yellow borders, and blue spots. Ready to take flight, you’ll now look for mates to continue the cycle. Males and females seek each other out during the spring and early summer (June and July), mating and producing the next generation.

As an adult, you have a unique ability to overwinter, or hibernate, in order to survive harsh weather conditions. This process, called diapause, allows you to live longer compared to other butterflies. This fascinating life cycle continues as you and other mourning cloak butterflies perpetuate the next generation, ensuring the survival of your species.

Habitats and Geographical Distribution

Mourning cloak caterpillars mainly thrive in hardwood forests across the northern hemisphere. You’ll find them widely dispersed throughout North America, ranging from Canada south to Florida, and extending west to Montana. They are also present in Eurasia, but their range doesn’t extend to South America.

As a butterfly enthusiast, you might encounter these caterpillars near lakes and ponds, or even in parks and gardens. They’re particularly fond of aspen, ash, and other hardwood trees. Be on the lookout when visiting places like North Carolina, Wisconsin, and Mexico, where these beautiful caterpillars reside.

During the winter season, adult Mourning Cloaks can endure harsher conditions compared to other butterflies. They have been observed overwintering in various parts of their North American range. While they’re less active during the colder months, they emerge in full force when temperatures rise.

To sum it up, here are some key features of Mourning Cloak caterpillars’ habitats and distribution:

  • Predominantly found in hardwood forests
  • Widespread across the northern hemisphere
  • Favor aspen, ash, and other hardwood trees
  • Inhabit parks, gardens, lakes, and ponds
  • Survive in a broad range of climates, from Canada to Florida
  • Can overwinter in colder regions

Now you know where to spot these fascinating creatures. So next time you explore hardwood forests, parks, or gardens, pay close attention to those beautiful Mourning Cloak caterpillars – they might just be hiding in plain sight.

Species of the Mourning Cloak

The Mourning Cloak, scientifically known as Nymphalis antiopa, is a unique species of butterfly belonging to the Nymphalidae family. They’re also called brush-footed butterflies due to the unique structure of their first pair of legs. Here are some of their notable features:

  • Wingspan: They have a wingspan ranging from 2.5 to 4 inches.
  • Color: The adults are dark brown with a distinctive yellow or white band on the outer edge of their wings and a row of blue spots.
  • Habitat: Mourning Cloaks are commonly found in North America, Europe, and Asia, with a preference for wooded areas.

As for the Mourning Cloak caterpillar, its diet primarily consists of the leaves from trees like willow, elm, and aspen. When caterpillars hatch, they feed gregariously in groups before becoming more solitary as they grow. Feeding on these leaves allows them to store enough nutrients to transform into the beautiful butterflies we know them as.

In spring, the adults emerge, feeding on tree sap and nectar from early-blooming flowers. Their preference for sap and rotting fruit makes them less dependent on flowers compared to other butterfly species.

Here’s a comparison between Mourning Cloaks and a related moth:

Feature Mourning Cloak Butterfly Moth (Lepidoptera)
Wingspan (average) 2.5 to 4 inches varies
Antennae clubbed feathery
Spines on Caterpillar present varies
Wing Coloration bright, with bands usually dull

Mourning Cloak butterflies play a crucial role in their environment as pollinators, just like other butterflies and moths. By choosing the right plants for your garden, you can help support these beautiful creatures and contribute to maintaining a healthy ecosystem.

Interactions with other Species

Mourning cloak caterpillars, also known as spiny elm caterpillars, are fascinating creatures due to their interactions with other species. In this section, we will explore some of these interactions.

First, let’s look at the predators of mourning cloak caterpillars. As caterpillars, they are especially vulnerable to various predators like birds, parasitic wasps, or even larger insects. Their spiny appearance may deter some predators, but many still manage to feed on mourning cloak caterpillars.

As for pollinators, the adult mourning cloak butterfly lures pollinators when they go out to collect nectar from various flowers. They tend to feed on tree sap and fruits, so their interactions with pollinator species are not as prominent as other butterflies.

It is worth noting that mourning cloak butterflies display territorial behavior. The males are known to establish their own territories and fly aggressively to defend against intruders. Sometimes they even engage in lekking, where multiple males gather to perform courtship displays to attract females.

In terms of mating behavior, mourning cloak butterflies are polygynous, meaning each male may mate with multiple females. This leads to a competitive environment where males must be not only territorial but also showcase their attractive traits to woo multiple partners.

To sum up, the interactions of mourning cloak caterpillars with other species are quite intriguing. From predation pressure to territorial defense and unique mating behavior, these insects display numerous adaptations to thrive in their ecosystems.

Additional Information

Overwintering and Dormancy

Mourning Cloak caterpillars are known for their unique ability to overwinter. This means they spend their winter months in a state of dormancy. They often find shelter in tree cavities or other protected areas to survive the cold months.

Feeding Habits

These caterpillars are defoliating feeders, meaning they consume leaves of various plants. They have a preference for deciduous trees such as elm and willow, but can also be found on poplars and cottonwoods. The caterpillars will often feed on the same tree where the eggs were laid.

State Insect and Classification

Although the Mourning Cloak is not a state insect, its close relative, the Eastern Tiger Swallowtail, holds that title in several states. Both belong to the order Lepidoptera and are species of butterflies found in North America. You can find these beautiful creatures in guidebooks like “Butterflies Through Binoculars” and “Butterflies of North America.”

Physical Characteristics

Mourning Cloak caterpillars are quite distinctive in appearance. They have:

  • Black bodies with rows of red spots
  • Spiny projections on their bodies

These features help differentiate them from similar species, such as the Spiny Elm Caterpillars, which lack the red spots.

In conclusion, Mourning Cloak caterpillars are fascinating creatures with unique overwintering abilities and noticeable physical characteristics. By knowing more about their feeding habits and classification, you can better understand and appreciate these remarkable insects.


  1. Mourning Cloak Butterfly / Spiny Elm Caterpillar

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Morning Cloak Caterpillar aggregation


Gathering of Mourning Cloak ”Cats”
Location: Marsh area, N. Ohio
June 27, 2011 10:16 am
Dear Bugman: I spotted this cluster of Mourning Cloak caterpillars, while on a nature trail in a northern Ohio marsh.
I have never seen so many of these cats gathered all together before. At first I thought they we some kind of tent caterpillar. They were feeding on willow leaves.
I noticed an interesting behavior. While some ”cats” were eating, others kept their heads up and made jerking, bobbing motions with them, all in unison. It was like synchronized head bobbing. Is this some kind of defense or early warning system behavior?
Signature: Chrstine O.

Morning Cloak Caterpillars

Hi Christine,
We love your photograph.  Caterpillars that form aggregations by remaining in close proximity to one another while feeding and resting generally derive benefits from the safety in numbers notion.  While we cannot comment specifically on the head bobbing you witnessed, your hypothesis is consistent with a defense explanation.  Morning Cloak Caterpillars will remain in a communal state until they are ready to pupate, though often the chrysalides are also found in “colonies”, though the metamorphosis generally occurs away from the food plant.  It has been our observation that this year we have seen more Mourning Cloak Butterflies in Los Angeles than in any year in recent memory.  It seems from the mail that we have received that there may be a spike in the population of Mourning Cloak butterflies and caterpillars this year.  Often population advances and declines are cyclical.  Perhaps the unseasonal rains in both the Pacific Southwest and in the Mid West this year are responsible for the population surge.


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    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

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