The Anise Swallowtail caterpillar is a fascinating creature with specific dietary habits that play a crucial role in its growth and development.
Native to Western North America, this caterpillar’s choice of food not only ensures its survival but also prepares it for its eventual transformation into the Anise Swallowtail butterfly.
This article delves deep into understanding what the Anise Swallowtail caterpillar eats, why it chooses certain plants, and how its diet impacts its life cycle.
Let’s explore the dietary world of this intriguing caterpillar.
Physical Characteristics & Identification
Caterpillar
The Anise Swallowtail caterpillar, scientifically known as Papilio zelicaon, is a captivating creature that undergoes significant transformations in its appearance as it progresses through its developmental stages.
In its early instars, the caterpillar is predominantly dark brown, almost black, which might be a strategy to resemble bird droppings, a common form of camouflage among caterpillars.
This dark hue is punctuated by an irregular white band around its middle, giving it a distinctive look. As it grows and moves through successive molts, the caterpillar begins to exhibit a shift in its color palette.
The dark brown starts to give way to shades of green. By the time it reaches its fifth and final instar, the caterpillar boasts a predominantly green body.
This vibrant green is adorned with markings in black, orange, and light blue, making it a visual treat and easily distinguishable from many other caterpillar species.
Another fascinating aspect of its physical characteristics is the presence of bright orange osmeteria, or “stinkhorns”, which are eversible glandular structures located just behind its head.
When threatened, the caterpillar can protrude these structures as a defense mechanism, releasing a foul odor to deter potential predators.
Anise Swallowtail Butterfly
The Anise Swallowtail butterfly, the mature form of the Papilio zelicaon caterpillar, is a strikingly beautiful creature that captures the essence of nature’s artistry.
Upon emerging from its chrysalis, the Anise Swallowtail reveals its large, vibrant wings that span anywhere from 2 ¾ to 3 ½ inches.
The primary color of the wings is yellow, interspersed with black bands and spots.
The forewings showcase a series of black bands, while the hindwings are adorned with a blue crescent and an orange-red eyespot near the tail.
This combination of colors not only makes the butterfly visually appealing but also aids in confusing or deterring potential predators.
One of the most distinguishing features of the Anise Swallowtail, as with other swallowtails, is the presence of the “tail” on the hindwings.
These tails, along with the red eyespots, mimic the appearance of antennae, potentially confusing predators about the butterfly’s head orientation and giving the butterfly a chance to escape when under threat.
The underside of the butterfly’s wings is equally mesmerizing. It is paler in color, with the yellow regions appearing more cream-like, and the black, blue, and red patterns appearing more subdued.
This coloration provides excellent camouflage when the butterfly is resting on flowers or foliage.
In flight, the Anise Swallowtail is graceful and agile. Its wing patterns create a mesmerizing visual as it flits from flower to flower, making it a favorite among butterfly enthusiasts and photographers alike.
Life Cycle, Metamorphosis, and Lifespan of the Anise Swallowtail
Life Cycle and Metamorphosis
- Egg: The life of an Anise Swallowtail begins as a tiny, spherical egg, usually laid on the leaves of host plants, particularly those in the carrot family. Depending on the temperature and conditions, the egg will hatch in a few days to a couple of weeks.
- Caterpillar (Larva): Once hatched, the caterpillar emerges, and its primary goal is to eat and grow. As it consumes the leaves of its host plant, it undergoes several molting stages, shedding its skin to accommodate its growing body. This larval stage lasts for several weeks.
- Pupa (Chrysalis): After reaching its full size, the caterpillar finds a secure spot, often on twigs or stems, to form its chrysalis. Within this protective casing, the caterpillar undergoes a remarkable transformation, rearranging its cells and body structure. This pupal stage can last from a couple of weeks to several months, depending on environmental conditions.
- Butterfly (Adult): From the chrysalis emerges the adult Anise Swallowtail butterfly. With its vibrant wings, it is now ready to fly, mate, and lay eggs, thus completing the life cycle.
How Long Do Anise Swallowtail Butterfly Live?
The adult Anise Swallowtail butterfly, once emerged from its chrysalis, typically has a lifespan ranging from six to fourteen days
What Do Anise Swallowtail Caterpillars Eat?
The Anise Swallowtail caterpillar, like many caterpillars, is selective about its food sources, displaying a strong preference for specific plants that provide the necessary nutrients for its growth and development.
Central to its dietary choices is the carrot family, or Apiaceae, a group of aromatic plants that are not only essential for the caterpillar’s sustenance but also play a role in its survival strategy.
Sweet fennel and wild fennel stand out as the primary host plants for the Anise Swallowtail caterpillar.
These plants not only offer the caterpillar a rich source of nutrition but also provide a habitat where the caterpillar can thrive, grow, and eventually metamorphose into its butterfly form.
The aromatic nature of fennel might also play a role in deterring certain predators, offering the caterpillar an added layer of protection.
While sweet and wild fennel are the caterpillar’s primary choices, its palate is not limited to these plants alone.
The caterpillar is also known to feed on other members of the carrot family.
Parsley, with its lush green leaves, offers another nutritious food source.
Dill, another aromatic herb from the Apiaceae family, is also occasionally part of the caterpillar’s diet.
These plants, with their distinct flavors and aromas, not only nourish the caterpillar but might also influence the taste or smell of the caterpillar, potentially making it less appealing to certain predators.
To summarize:
- Primary Host Plants: Sweet fennel and wild fennel are the caterpillar’s primary food sources, providing essential nutrients and a suitable habitat.
- Additional Food Sources: Beyond fennel, the caterpillar also consumes other plants from the Apiaceae family, including Parsley and Dill
What Does Anise Swallowtail Butterflies Eat?
The Anise Swallowtail butterfly, upon reaching its mature form, undergoes a significant shift in its dietary preferences.
Unlike its caterpillar stage, which feeds primarily on specific plants from the carrot family, the butterfly is drawn to the sweet nectar of flowers.
Nectar serves as the primary source of energy for the Anise Swallowtail butterfly, providing it with the essential sugars and nutrients required for its daily activities, including flight, reproduction, and defense.
The butterfly’s proboscis, a long, tube-like tongue, is perfectly adapted for sipping nectar from the depths of flowers.
As for the flowers they are attracted to, the Anise Swallowtail butterfly has a range of preferences. Some of the common flowers that these butterflies frequent include:
- Lilac: Known for its fragrant clusters of flowers.
- Coneflowers: Recognizable by their large, daisy-like appearance.
- Milkweed: A favorite among many butterfly species, not just the Anise Swallowtail.
- Goldenrod: Tall plants with bright yellow flowers.
- Zinnias: Colorful flowers that come in a variety of hues.
- Marigolds: Bright orange or yellow flowers that are common in gardens.
- Phlox: Clusters of pink, purple, or white flowers.
Habitat and Distribution of the Anise Swallowtail Caterpillar
Geographical Distribution
The Anise Swallowtail caterpillar is predominantly found in regions of Western North America.
This includes areas stretching from Alaska down to Baja California and even as far east as the western Great Plains.
These regions offer the ideal climate, vegetation, and protection for the caterpillar to grow and metamorphose into its butterfly form.
Habitat
Proximity to Food Plants: Given its dietary preference for plants from the carrot family, especially sweet and wild fennel, these caterpillars are often found in areas where these plants are abundant.
This ensures that the caterpillar has a consistent and readily available food supply, crucial for its rapid growth and development.
Gardens: Due to the popularity of plants like parsley, dill, and fennel in home gardens, it’s not uncommon to find Anise Swallowtail caterpillars in residential areas.
Gardeners might spot them munching on their herb plants, and while they might be seen as pests, they are a testament to a healthy, pesticide-free garden.
Hilltops: An interesting behavior of the mature Anise Swallowtail butterfly, which indirectly affects the caterpillar’s habitat, is hilltopping.
Adult butterflies often fly to hilltops for mating rituals. As a result, caterpillars can sometimes be found in regions surrounding these hilltops, indicating the butterfly’s preference for laying eggs in these areas.
Unique Behavioral Traits and Defense Mechanisms
The Anise Swallowtail caterpillar, while delicate in appearance, is equipped with a set of intriguing behavioral traits and defense mechanisms that ensure its survival in the wild.
These adaptations not only protect the caterpillar from potential threats but also offer a glimpse into the intricate ways nature equips its creatures for survival.
Osmeteria (Horns) and Their Role
One of the most distinctive defense mechanisms of the Anise Swallowtail caterpillar is the presence of osmeteria, often referred to as “stinkhorns.”
These are forked, bright orange glandular structures located just behind the caterpillar’s head.
Typically hidden, the osmeteria are everted or pushed out when the caterpillar feels threatened.
When exposed, they release a foul-smelling chemical, which serves multiple purposes.
Firstly, the odor can deter potential predators, making them think twice before making a meal of the caterpillar.
Secondly, the bright orange color of the osmeteria can be startling, adding another layer of defense by visually warning off threats.
Are Anise Swallowtail Caterpillars Poisonous?
A common question that arises, given the caterpillar’s defense mechanisms, is whether they are poisonous.
While the osmeteria emit a foul odor, the caterpillar itself is not considered toxic or harmful when touched.
However, the chemicals released from the osmeteria might cause mild irritation to some individuals, especially if they come into contact with sensitive areas like the eyes.
It’s always advisable to handle any wildlife, including caterpillars, with care and to wash hands after touching them.
Potential Threat to Predators
For predators, the combination of the caterpillar’s odor and potential taste deterrence (from feeding on aromatic plants like fennel) makes the Anise Swallowtail caterpillar a less-than-appealing meal choice.
While not toxic in the traditional sense, the caterpillar’s defense mechanisms effectively reduce its chances of being preyed upon.
What To Feed Swallowtail Caterpillars?
Swallowtail caterpillars, belonging to the family Papilionidae, are a diverse group with various species having specific dietary preferences.
While the Anise Swallowtail caterpillar has its favorites, other swallowtail caterpillars also have their unique host plants.
General Dietary Preferences
Swallowtail caterpillars are herbivores, feeding primarily on the leaves of specific host plants. These plants provide the caterpillars with essential nutrients, allowing them to grow and eventually metamorphose into butterflies.
Specific Preferences
- Eastern Black Swallowtail (Papilio polyxenes): This caterpillar prefers plants in the carrot family (Apiaceae). Common host plants include parsley, dill, fennel, and Queen Anne’s lace.
- Giant Swallowtail (Papilio cresphontes): These caterpillars often feed on citrus trees. This includes oranges, lemons, limes, and grapefruits.
- Spicebush Swallowtail (Papilio troilus): Their primary diet consists of spicebush (Lindera benzoin) and sassafras trees (Sassafras albidum).
- Eastern Tiger Swallowtail (Papilio glaucus): They have a varied diet, feeding on trees like tulip trees (Liriodendron tulipifera), black cherry (Prunus serotina), and plants like sweetbay magnolia (Magnolia virginiana).
- Zebra Swallowtail (Eurytides marcellus): These caterpillars feed on plants in the pawpaw family (Annonaceae), specifically the pawpaw tree (Asimina triloba).
- Pipevine Swallowtail (Battus philenor): Their diet revolves around plants known as pipevines or Dutchman’s pipevines (Aristolochia species).
- Anise Swallowtail (Papilio zelicaon): As previously discussed, their primary diet includes sweet fennel, wild fennel, and other plants in the carrot family.
Considerations When Feeding
If you’re raising swallowtail caterpillars, it’s essential to provide fresh leaves from their specific host plants.
Ensure that the plants are free from pesticides, as these can harm or kill the caterpillars.
Regularly replenish the food source, especially as the caterpillars grow and their appetites increase.
Caring for a Swallowtail Caterpillar
Raising a swallowtail caterpillar can be a rewarding experience. However, to ensure the health and successful development of the caterpillar, certain guidelines and care practices should be followed.
- Enclosure: Use a well-ventilated container or netted cage as an enclosure. This provides protection from predators while ensuring adequate airflow.
- Temperature and Humidity: Swallowtail caterpillars thrive in mild temperatures and moderate humidity. While they can tolerate a range of conditions, extreme cold or heat can be detrimental. If raising them indoors, keep them away from direct sunlight or cold drafts.
- Sticks and Twigs: Place some sticks or twigs inside the enclosure. These will serve as structures for the caterpillar to crawl on and eventually form its chrysalis.
- Cleanliness: Regularly clean the enclosure to remove waste (frass) and any old or uneaten food. This helps prevent mold growth and maintains a healthy environment.
- Hydration: While caterpillars get most of their water from the food they eat, it’s a good practice to occasionally mist the enclosure with water, ensuring they have adequate hydration.
- Observation: Keep a close eye on the caterpillar’s behavior. If it stops eating or seems lethargic, it might be preparing to pupate. Alternatively, it could be a sign of stress or illness.
- Preparation for Pupation: As the caterpillar nears the end of its larval stage, it will start looking for a suitable spot to form its chrysalis. Ensure there are ample places within the enclosure where it can securely attach itself.
Conclusion
In summary, the Anise Swallowtail caterpillar primarily feeds on plants from the carrot family, especially favoring sweet fennel and wild fennel.
As it grows, it might also consume other plants from the same family, such as parsley and dill.
These specific dietary choices provide the caterpillar with essential nutrients for its development.
The caterpillar’s preference for these plants not only ensures its nourishment but also plays a role in its survival, as the aromatic nature of these plants may deter certain predators.
This dietary focus is crucial for its successful metamorphosis into the Anise Swallowtail butterfly.
3 Comments. Leave new
I believe this could also be a caterpillar of Pike’s Old World Swallowtail, *Papilio machaon pikei* (http://www.entomology.ualberta.ca/searching_map.php?fid=500761&vw=1&sb=1&r=41&o=1&c=1&s=2047&sn=Papilio+machaon+pikei).
Best wishes,
Keith Wolfe
Hi. I moved to North Eastern Pa a couple of years ago & have a small herb garden. But planted a lot of parsley this year. I spotted the Anise swallow Caterpillar today and just saw your site. Please tell me what happens to them and when do they go from caterpillar to butterflies? they are so pretty in this stage, and I definitely want to protect them from other predators. What would eat them? And how can I protect them?
Considering your location, you did not observe Anise Swallowtail Caterpillars, but rather Black Swallowtail Caterpillars, Papilio polyxenes. A web search should easily provide you with numerous images of an adult Black Swallowtail. BugGuide has information you has information you might find interesting. Prior to metamorphosis into the adult, the caterpillar transforms into a pupa. Predators include birds and wasps.