Is there any creature in the garden more mesmerizing and magical than caterpillars? These fascinating insects come in many different sizes and colors and display incredible camouflage, mimicry, and defense mechanisms.
Caterpillars feed on “host plants,” specific plants that provide essential nutrients required for their growth and development. These plants play a crucial role in the life cycle of butterflies and moths, supporting their larvae until they are ready to pupate and transform into adult insects.
Some caterpillars are specialists, relying on a narrow range of host plants, which can make them more vulnerable to habitat changes. Others are generalists, feeding on a wide variety of plants, which allows them to adapt more easily to different environments and food sources.
Even more incredible, caterpillars undergo a remarkable transformation, turning into beautiful butterflies or moths.
During this metamorphosis, caterpillars transform into a chrysalis, break down into a soup-like substance, and then reassemble into their adult form. If that doesn’t make you marvel at the humble caterpillar, nothing else will!
My Love of Caterpillars
Caterpillars have become one of my favorite creatures to find, observe, photograph, and support in my garden. Even as a child, I would collect caterpillars in jars, filling them with blades of grass and sticks to form their habitat and having my dad punch holes in the jar lid for air. Then I’d wait patiently for them to make their chrysalis and transform into whatever winged creature their DNA had programmed them to become.
One summer an older cousin was visiting from California. I proudly showed him my collection of tent caterpillars. He thought it would be funny to hide my jar from me, so he placed it up high on a ledge of the rock wall that surrounded our house.
As I climbed that ledge to retrieve my jar I slipped and fell hard hitting my chin on the rocks. That resulted in a trip to the ER, stitches, and a scar I will always bear to remind me of my love for caterpillars.
As an adult, things haven’t changed much. I still collect a portion of the caterpillars I find to raise, observe, and photograph their transformation. Sometimes I find them on the native plants in my garden, and other times they are thriving on introduced plants like herbs.
Regular Garden Visitors
In this article, I am sharing many of the caterpillars I’ve photographed in my garden over the years, what plants they need to survive, and what pollinators they turn into. And in many cases, I also have photos of them in chrysalis form.
You might recognize a few of these in your garden or landscape, and if you do, I hope you welcome them in and watch what they grow up to be.
Meet the Swallowtail Caterpillars
Swallowtail caterpillars are some of the most fascinating and visually striking visitors you can find in your garden and some of the first ones I photographed.
Belonging to the family Papilionidae, these caterpillars transform into beautiful butterflies known for their large size, vibrant colors, and distinctive tail-like extensions on their hind wings, which resemble the forked tails of swallows.
Swallowtails caterpillars are often seen munching on the leaves of various host plants found in gardens. They also have a unique characteristic called osmeterium that resemble bright orange horns. When threatened, the caterpillar everts the osmeterium to release foul-smelling chemicals that deter predators.
Eastern Black Swallowtail
The first swallowtail I ever encountered in the garden was the Eastern Black Swallowtail (Papilio polyxenes). It’s a striking and familiar visitor to many gardens in North America. I discovered the caterpillars eating my parsley and wasn’t sure what they were. They were the “gateway” caterpillar for me. Researching what they were and why they were destroying my parsley plant led me to discover the concept of host plants.
Known for its distinctive black wings adorned with yellow spots and a row of blue crescents near the tail, this butterfly is as beautiful as it is beneficial. If you want to host this caterpillar, be prepared to plant and sacrifice some of your more popular herbs that are in the carrot family.
Eastern Black Swallowtail Facts
Scientific Name: Papilio polyxenes
Host Plants: (Apiaceae family): Parsley, dill, fennel, carrot, celery, caraway and Queen Anne’s lace | Occasionally Rue (Ruta graveolens)
Range: Throughout the eastern and central United States, extending into the southwestern states.
Eastern Black Swallowtail Caterpillar Instars
Black Swallowtail caterpillars go through five instars:
1st Instar: Very small and black with a white saddle.
2nd and 3rd Instar: Continue to be black with a white band, resembling bird droppings.
4th Instar: Starts showing green coloration with black bands and spots.
5th Instar: Fully developed with green and black banding and yellow spots, reaching the maximum size before pupation.
Giant Swallowtails
The Giant Swallowtail (Papilio cresphontes) is one of the largest and most impressive butterflies found in North America. With a wingspan reaching up to six inches, this butterfly is easily recognized by its striking dark brown to black wings adorned with yellow bands and spots.
The caterpillars, known for their bird-dropping mimicry, primarily feed on citrus plants and other members of the Rutaceae family. I have a giant rue plant in the garden that hosts these caterpillars every year, all season long.
Giant Swallowtail Facts
Scientific Name: Papilio cresphontes
Host Plants: Rue, common citrus plants (orange, lemon, lime) (Rutaceae family)
Range: Southeastern United States, extending into the central U.S. and parts of California.
Giant Swallowtail Caterpillar Instars
Giant Swallowtail (Papilio cresphontes) caterpillars go through five instar stages before pupating and transforming into butterflies.
1st Instar: Tiny, dark brown to black caterpillars with a white saddle-like patch in the middle, resembling bird droppings, which serves as a form of camouflage.
2nd Instar: The caterpillars remain small and continue to mimic bird droppings. They become slightly larger and the white patch becomes more prominent.
3rd Instar: Caterpillars start to develop more noticeable patterns. Their body lengthens, and the coloration includes more defined white and brown markings.
4th Instar: The caterpillars are significantly larger with more distinct patterning of brown, white, and sometimes greenish hues with the bird-dropping mimicry is less pronounced.
5th Instar: The final instar is the largest and most distinctive. Caterpillars are brown with white splotches and can reach up to 5 centimeters in length. The osmeterium is fully developed and more readily used when threatened. It’s during this phase that they remind me of little snakes.
Spicebush Swallowtails
The Spicebush Swallowtail (Papilio troilus) has quickly become one of my favorite caterpillars. It’s a unique caterpillar that resembles a small snake that primarily feeds on Spicebush (Lindera benzoin) and ther plants in the Laurel (Lauraceae) family, such as sassafras.
The caterpillars’ impressive mimicry of a snake, complete with large false eyespots, helps deter predators and ensures their survival. I love these so much, I dedicated an entire post just to Spicebush Swallowtail detailing their mimicry behavior and how I brought them to my garden.
Spicebush Swallowtail caterpillars also exhibit a fascinating behavior known as leaf-rolling, which plays a critical role in their survival. This behavior involves the caterpillars manipulating leaves with silk production forming a shelter, providing protection from predators and harsh environmental conditions.
Spicebush Swallowtail Facts
Scientific Name: Papilio troilus
Host Plants: Spicebush, sassafras (Lauraceae family)
Range: Eastern United States, from Florida to southern Canada and west to Texas and Oklahoma.
Spicebush Swallowtail Caterpillar Instars
Spicebush Swallowtail (Papilio troilus) caterpillars go through five instar stages before pupating.
1st Instar: The first instar caterpillars are tiny and brownish-black, resembling bird droppings. This coloration provides camouflage against predators.
2nd Instar: The caterpillars continue to resemble bird droppings, but they begin to develop a more distinct brownish coloration with some white markings.
3rd Instar: During the third instar, the caterpillars start to develop the characteristic false eyespots on their thorax. These eyespots are initially small and less prominent.
4th Instar: The caterpillars become larger and the false eyespots become more pronounced. Their color may shift to a lighter greenish-brown, enhancing their mimicry of a snake.
5th Instar: In the final instar, the caterpillars are bright green with large, vivid yellow and black eyespots on their thorax, making them resemble a small snake. This coloration and mimicry serve to deter predators.
Discovering Fritillaries
Fritillaries are a fascinating group of butterflies that bring dynamic color and life to gardens and natural spaces. With species such as the Variegated Fritillary (Euptoieta claudia) and the Gulf Fritillary (Agraulis vanillae), these butterflies are easily recognized by their vibrant orange wings adorned with intricate patterns of black and silver spots.
Fritillary caterpillars are versatile feeders, thriving on host plants like violets, and passionflowers. I was also recently surprised to find variegated frits eating some wild wood sorrel in the garden.
The Gulf Fritillary
The Gulf Fritillary (Agraulis vanillae) frequents my garden all season. The Gulf Frit is a striking and vibrant butterfly commonly found in the southern United States, Central America, and parts of South America. It is easily recognized by its bright orange wings adorned with black spots and silvery-white spots on the underside.
To observe the caterpillars of this one, you’ll have to grow its host plant passion flower. Passion flower can be started from seed or cuttings. If you’re lucky enough to have a garden center that sells native plants and you see passion flower there, plant it and enjoy its flowers and the life it brings to the garden!
Gulf Fritillary Facts
Scientific Name: Agraulis vanillae
Host Plants: Passionflower (Passifloraceae family)
Range: Southern United States, from Florida to Texas and up the East Coast to the Carolinas, also present in California.
Gulf Fritillary Caterpillar Instars
Gulf Fritillary caterpillars go through five instar stages before pupating and transforming into adult butterflies.
1st Instar: Newly hatched caterpillars are tiny and dark orange with black spines.
The first instar caterpillars begin feeding on the leaves of their host plant, passionflower (Passiflora species). They consume the eggshell after hatching, which provides additional nutrients.
2nd Instar: The caterpillars grow larger and their spines become more pronounced. They remain orange with black spines.
3rd Instar: The caterpillars become more robust, with their orange color becoming more vivid and their black spines more prominent.
4th Instar: Caterpillars are now significantly larger and maintain their orange and black coloration. Their spines are more noticeable, providing a deterrent to predators.
5th Instar: Final instar caterpillars reach their maximum size, often measuring up to 4.5 cm in length. They are bright orange with black spines and white spots.
At this stage, the caterpillars prepare for pupation by searching for a suitable location to form their chrysalis. They consume large quantities of leaves to store energy for the metamorphosis process.
The Variegated Fritillary
The Variegated Fritillary (Euptoieta claudia) caterpillars primarily feed on plants in the violet family (Violaceae) and passionflower family (Passifloraceae), but to my surprise, I found them using wood sorrel this year as a host.
Wood sorrel is a wild edible that contains oxalic acid which gives it a sour taste. As kids, my siblings and I chewed it when we’d find it while playing outdoors. We always called it “sheep showers.” I guess variegated fritillaries enjoy the flavor from time to time when its other host plants are not available.
I’ve only gotten photos of the earlier instars for this one as well as the adult butterfly. I was also extremely lucky to also come across a chrysalis in the garden.
This butterfly is easily recognized by its orange-brown wings, though not as flashy as the Gulf Frit. It’s adorned with black spots and intricate patterns that give it a variegated appearance. The underside of the wings is mottled with browns and grays, providing effective camouflage.
Variegated Fritillaries are frequent visitors to gardens, open fields, and roadsides, where they feed on nectar from various flowers.
Variegated Fritillary Facts
Scientific Name: Euptoieta claudia
Host Plants: Violets, passionflowers, pansies, wood sorrel (Violaceae, Passifloraceae, and Oxalidaceae families)
Range: Throughout the United States, most common in the south and central regions.
Variegated Fritillary Caterpillar Instars
Variegated Fritillary caterpillars go through five instar stages before pupating. They’re so alike to Gulf Fritillaries so to identify them, I had to pay attention to their host plant and submit photos on iNaturalist to get help distinguishing between the two.
1st Instar: Newly hatched caterpillars are small and black with short spines. They often display a light brown or yellowish band along the length of their bodies.
The first instar caterpillars start feeding on the leaves of their host plants, such as violets and passionflowers. They consume the eggshell after hatching, which provides additional nutrients.
2nd Instar: The caterpillars grow larger, and their spines become more pronounced. They retain their black coloration with the light band along their bodies.
3rd Instar: The caterpillars become more robust, with black spines and a more pronounced yellowish or brownish band. They develop additional white or yellow spots.
4th Instar: The caterpillars are now significantly larger and maintain their black coloration with yellowish bands and spots. Spines are more noticeable, providing a deterrent to predators.
5th Instar: The final instar caterpillars reach their maximum size, often displaying vivid black, yellow, and white markings. Their spines are long and prominent.
At this stage, the caterpillars prepare for pupation by searching for a suitable location to form their chrysalis. They consume large quantities of leaves to store energy for the metamorphosis process.
Painted Ladies
The “Ladies” butterflies, encompassing species like the American Lady (Vanessa virginiensis) and the Painted Lady (Vanessa cardui), bring vibrant color to gardens across the United States.
They are known and loved for their striking orange, black, and white wing patterns. Their caterpillars feed on a variety of host plants, including pussytoes, pearly everlasting, cudweed, thistles, mallows, and hollyhocks, making them a vital part of the garden ecosystem. This year, I was surprised to find Painted Lady caterpillars curled up in and feeding on the leaves of my Mugwort (Artemisia vulgaris) plant!
Painted Lady Facts
Scientific Name: Vanessa cardui
Host Plants: Thistles, mallows, hollyhocks (Asteraceae and Malvaceae families), and I have found them also using Artemisia vulgaris.
Range: Throughout the United States, from coast to coast and into Canada.
Painted Lady Caterpillar Instars
1st Instar: The newly hatched caterpillars are tiny and black with bristly hairs, displaying a white band or saddle-like marking across the middle of their bodies.
During the first instar, caterpillars feed on the leaves of their host plants, such as thistles, mallows, and hollyhocks. They remain near the site of egg hatching and consume the eggshell for additional nutrients.
2nd Instar: As they grow, the caterpillars retain their dark coloration but become larger and more robust. The white band may still be visible, and the body is covered with more noticeable bristles.
3rd Instar: Caterpillars grow larger and start to develop more pronounced striping and spines. Their black coloration may lighten slightly, and the body becomes more segmented in appearance.
The caterpillars are now more mobile and feed extensively on the leaves, sometimes creating silken nests or shelters for protection. This is how I was alerted to their presence. The rolled up mugwort leaf below with silky webbing told me something was hiding inside.
4th Instar: The caterpillars are significantly larger and exhibit clearer striping with yellow and black bands. Spines and bristles are more developed, providing additional defense against predators.
5th Instar: In the final instar, the caterpillars reach their maximum size, often displaying vivid black, yellow, and white striping. The spines are prominent, and the body is robust and heavily segmented.
And Of Course, Monarch Caterpillars
You didn’t think I’d forget these, did you? One of the first caterpillars we ever “raised” and specifically planted host plants for, the Monarch Danaus plexippus has gotten a lot of publicity over the past several years due to the decline in populations.
Habitat loss is a primary issue, as urban development and agricultural expansion reduce the availability of milkweed, the sole host plant for Monarch caterpillars. Pesticide use further diminishes milkweed populations and directly harms Monarchs. Additionally, climate change disrupts their migratory patterns and deforestation of overwintering sites in Mexico, are impacting their survival.
Monarchs are one of the most iconic and beloved butterflies in North America. Known for its migratory journey, the Monarch travels thousands of miles between its breeding grounds in the United States and Canada and its wintering sites in Mexico.
Monarch caterpillars feed exclusively on milkweeds, making these plants essential for their survival. They pass right over Oklahoma on their way from and back to Mexico, so I get a few in the spring and lots more in the fall.
By planting native milkweeds, gardeners can play a pivotal role in supporting the Monarch’s life cycle and conservation efforts.
Monarch
Scientific Name: Danaus plexippus
Host Plants: Milkweeds (Asclepiadaceae family)
Range: Throughout the United States, with seasonal migrations extending into Canada and Mexico.
Instar Stages of Monarch Caterpillars
Monarch (Danaus plexippus) caterpillars undergo five distinct instar stages, each characterized by changes in size, appearance, and behavior.
1st Instar: Newly hatched caterpillars are tiny, measuring about 2-6 mm in length. They are pale greenish or translucent white with a black head capsule. The body appears slightly fuzzy due to tiny hair-like structures.
In their first instar, caterpillars primarily feed on the surface layer of milkweed leaves, often consuming their eggshell for additional nutrients. They stay close to the hatching site and are relatively inactive.
2nd Instar: The caterpillars grow to about 6-9 mm in length. They begin to show more distinct coloration, with black, white, and yellow bands becoming visible. The body becomes smoother, and the head capsule is still black.
3rd Instar: Caterpillars reach about 10-14 mm in length. The black, white, and yellow bands are now well-defined, and the body becomes more robust. Small tentacle-like filaments appear at both ends of the body, becoming more noticeable.
4th Instar: The caterpillars grow to about 13-25 mm in length. with the bands becoming more vibrant, and the body is significantly larger and thicker. Tentacle-like filaments at the front and rear of the body are more pronounced.
5th Instar: The final instar caterpillars can reach up to 45 mm in length. They are strikingly colorful with bold black, white, and yellow bands. At this stage, their tentacle-like filaments are fully developed, with the front pair being longer than the rear pair.
The caterpillars feed voraciously, consuming large quantities of milkweed leaves. As they near pupation, they may wander away from the host plant in search of a suitable pupation site.
Monarch Caterpillar Pupation
I’ve had the pleasure of raising Monarchs many times so I have watched the process from start to finish. Once they find a location to pupate, they will form a silk mat to secure themselves before hanging in a “J” shape to transform into a chrysalis.
The caterpillar forms a jade green chrysalis with gold spots, which provides effective camouflage against predators. Inside the chrysalis, the caterpillar undergoes metamorphosis, emerging as an adult butterfly after about 10-14 days, depending on environmental conditions.
The chrysalis experiences several fascinating changes, particularly as it nears the end of the pupation period. One of the most notable changes is the chrysalis turning dark, almost black, and becoming transparent, revealing the developing butterfly inside.
The Importance of Caterpillars in the Garden Ecosystem
Caterpillars, despite their reputation for munching on garden plants, play an essential role in both garden ecosystems and broader ecological networks. Their presence is a strong indicator of a healthy, thriving environment, and their contributions extend far beyond the leaves they consume.
Food Source for Wildlife: Caterpillars are a critical food source for a variety of wildlife, including birds, small mammals, reptiles, amphibians, and other insects like wasps and flies. Birds, in particular, rely heavily on caterpillars to feed their young.
During the breeding season, the protein-rich caterpillars provide the necessary nutrients for nestlings to grow and develop properly. A single pair of chickadees, for example, can consume thousands of caterpillars while raising their young.
Pollinators in the Making: While caterpillars themselves are not pollinators, the butterflies and moths they become are. Adult butterflies and moths visit flowers to feed on nectar, inadvertently transferring pollen from one bloom to another.
This activity supports the reproduction of many plant species, contributing to the biodiversity and resilience of ecosystems. The presence of caterpillars ensures a future generation of pollinators.
Inspiration and Education
Even if I hadn’t discovered the ecological benefits of caterpillars, I’d still find so much value in them. Observing caterpillars and their transformations into butterflies and moths offers valuable educational opportunities for adults and kids alike.
When I my daughter was growing up, finding caterpillars in the garden and watching them complete their lifecycle was an exciting way to show her Mother Nature in action. Even after all these years, we still search the garden each season to see who has shown up.
Observing caterpillars inspires a greater appreciation for the complexity of life cycles in nature and the interdependence of species within an ecosystem.
What About the Moths?
In addition to butterflies, I also have photographed quite a few moth caterpillars. Some of them decimate vegetables in the garden like cabbage if I don’t get on the ball and add barriers, but they’re just as fascinating and don’t always get as much love and attention as the butterflies. Maybe I’ll do a part two to this guide and showcase them as well.
Embracing Caterpillars and Increasing Biodiversity
These are just a few of the caterpillar varieties that have visited the garden over the years, and it doesn’t even include all the butterflies that I have photographed and never saw in caterpillar form like skippers, hairstreaks, sulphers, snouts, crescents, question marks, viceroys, queens, and more!
Once you learn about the caterpillars that are native to your region and the host plants they need, you can add those to your garden and watch and wait for them to show up!
Yes, caterpillars also eat some of the vegetables and herbs we grow. From that perspective, a gardener could see them as a pest. But you can also look at them as a partner in the garden – part of the bigger picture.
You can plant extra sacrificial crops for them and apply barriers to the plants you want to save for yourself. Add plants that you know they will eat and that you don’t mind taking some damage. That is what I do with rue that feeds the eastern black and giant swallowtails.
If your plants are being eaten by caterpillars, get excited! You are supporting one of the most miraculous and important lifeforms in nature.
