Caterpillar green and black

Worm Control On Parsley: Information On Deterring Parsley Worms

If you happened to notice worms on your parsley, dill, or an occasional carrot, chances are they are parsley worms. Read on to learn how to manage worms on parsley.

What are Parsley Worms?

Striking caterpillars, parsley worms turn into even more striking black swallowtail butterflies. They are easily identifiable as green worms with a brilliant, yellow dotted black band across each body segment. When the caterpillar is disturbed, it protrudes a pair of fleshy “horns,” the better to scare predators away. This larval stage of the gorgeous black swallowtail can grow up to 2 inches long.

Parsley Worm Life Cycle

Female black swallowtail butterflies are slightly larger than males and as is usual in nature a bit duller in color than their male counterparts. The wingspan may be up to 76 mm (3 in.). Both are velvety black in color with tailed hind wings marked with peacock-like eyes. The females lay spherical, 1 mm (0.03 in.) across eggs that change in color from pale yellow to reddish brown. Four to nine days later, the eggs hatch and young larvae (instars) emerge and begin feeding.

The yellowish-green parsley worm is the butterfly’s larval stage and its body is transverse with black bands and yellow or orange spots. The “horns” mentioned above are actually scent organs. The young larvae look similar but may have spines. The pupa or chrysalis appears dull gray and mottled with black and brown and is around 32 mm (1.25 in.). long. These pupae overwinter attached to stems or fallen leaves and emerge as butterflies in April-May.

How to Control Parsley Worms

Worm control on parsley is fairly simple, if you really desire their eradication. They are easy to spot and hand pick. They are also naturally attacked by parasites, or if you must, insecticides such as Sevin or Bacillus thuringiensis will kill off the caterpillars.

Although parsley worms are voracious eaters, the benefit of attracting a future pollinator (and a stunning one at that) may outweigh worm control practices on parsley. Me, I would just plant a few more parsley, dill or whatever the insects are feeding on. Healthy plants will usually recover from the foliage loss and parsley worms will not sting or bite humans.

Deterring parsley worms is a bit more difficult. If you find the caterpillars truly objectionable, you might try row covers. Covering your tender crops may aid in deterring parsley worms.

Transformations: Which Caterpillar Becomes Which Butterfly?

Eastern Tiger Swallowtail caterpillar. Photos by Gerry Lemmo.

The United Nations has coined 2010 to be The International Year of Biodiversity, so it’s only fitting that insects play a starring role in the pages of our summer issue. Insects, after all, are the most abundant animals on earth. While some species can be overlooked, due to their small size or out-of-the-way lifestyles, butterflies and caterpillars cannot. These veritable pop stars of the insect world – dolled up in coiffed hair tufts and shimmering wing scales – simply demand attention.

As any third-grader will tell you, Lepidoptera – the order of insects that includes butterflies and caterpillars – represent peak evolution in the cool-animal department. Sure, dogs and cats are great, but to even compete for the crown, Fido would have to shed his skin five or six times, then void his bowels, fashion himself a cocoon, digest his larval tissues and organs, and reemerge from the cocoon a few weeks later as a giant bird.

While the image of literal mammalian metamorphosis is silly, a philosophical interpretation is not. The human concept of redemption – this idea that we can change for the better – can be read into the caterpillar-to-butterfly progression. It’s no coincidence, then, that humans are attracted to butterfly totems, to tattoos and bejeweled winged amulets that rest against caterpillar-silk blouses. It’s no coincidence, then, that Hollywood filmmakers make hay here in the light version of human metamorphosis – the streetwalker-gone-good motif – and the dark side – the soul of great beauty who, like a butterfly, just can’t bring him- or herself to fly straight.

The influence that butterflies/caterpillars have on humans goes far beyond art and philosophy. In the world of raw economics, butterfly collectors still pay hundreds, if not thousands, of dollars for rare specimens. Farmers and foresters engage in epic battles with tree- and plant-munching larvae. One degree separate, but no less influential, is our human dependence on the relationship between caterpillars and plants. The aspirin you take for headaches is derived from salicylic acid, a plant compound that’s produced to thwart caterpillars. The coffee you may be drinking as you read this takes its bitter flavor from the same.

Back to square one now, the basic question that confronts every amateur naturalist when they gaze upon a caterpillar is: what kind of butterfly or moth will this become? You may know what a woolly bear looks like, but how about an Isabella tiger moth – the woolly bear’s adult form? Secondary questions include, what kind of food do they eat? And are they harmful if I touch them?

To answer these questions, we enlisted the help of photographer Gerry Lemmo and compiled photos of some of the most common caterpillars, and their subsequent butterflies or moths, that you’ll find in the Northeast. For more advanced studies, we’d suggest David L. Wagner’s Caterpillars of Eastern North America – an exceptional field guide – and Butterflies of the East Coast; An Observer’s Guide, by Rick Cech and Guy Tudor.

American Lady, Vanessa virginiensis

Description: Caterpillars vary in color, but the red bases of the hair tufts are usually a giveaway. Butterfly wingspan: 1¾–25/8 inches.

Ecology: American lady caterpillars are solitary creatures that feed in nests made out of silktied leaves. Favored fare includes pussytoes, ironweed, burdock, and plants in the sunflower family. Butterflies inhabit open places and are especially fond of aster, goldenrod, milkweed, and vetch.

Random Cool Fact: Like other “brush-footed” butterflies in the family Nymphalidae, American ladies have taste receptors on their feet that let them sample the flavor of a plant just by walking on it.

Black Swallowtail, Papilio polyxenes

Description: Larvae change dramatically with each molt; they start off looking like bird droppings and end up looking like the caterpillar pictured here. Butterfly wingspan: 1¾–25/8 inches. The butterfly pictured here is a female – males have less of that shimmering blue coloration and a more extensive yellow band.

Ecology: Caterpillars eat plants in the carrot family – look for them in the garden on dill, parsley, and fennel; in the wild, check out Queen Anne’s lace and poison parsnip. Black swallowtail butterflies eat nectar and, in an aesthetic irony, are attracted to mud and manure piles. They flourish around humans and open spaces; they’re declining as Northeastern farmland reverts back to forest.

Random Cool Fact: Caterpillars have retractable horns that emerge from a slit just behind their head when they’re alarmed.

Cecropia Moth, Hyalophora cecropia

Description: Sci-fi-looking caterpillars are frosted green and covered in shiny yellow, orange, and blue knobs. Moths are giant, with wingspans of 4¾–6 inches.

Ecology: Caterpillars eat many woody plants, including ash, apple, and box elder. Moths fly from April to July and are attracted to lights or, perhaps more accurately, are attracted to the darkness around bright lights.

Random Cool Fact: To pupate, a cecropia caterpillar folds itself into a leaf and secures its hideout with about a mile of silk.

Random Sad Fact: Native silk moths are all in decline – collateral damage in our war against the gypsy moth. When well-meaning but misguided scientists released tachinid flies in 1906 to kill gypsy moths, they didn’t count on the parasite having indiscriminate taste. Cecropias seem especially hard hit – in one Massachusetts study, 81 percent of lab-raised caterpillars that were released into the wild were parasitized by this exotic fly.

Luna Moth, Actias luna

Description: While beauty is subjective, most entomologists would be hard pressed to name an insect more beautiful than the luna moth. Larvae are lime green with faint pink spots and a pale stripe along the abdomen. Moths are otherworldly green with fern-frond antennae and pink, burgundy, white, and black eyespots. Wingspan can be wider than 4½ inches.

Ecology: Caterpillars eat a variety of tree leaves, including those of paper birch, sweet gum, hickory, and sumac. Adults live for about a week and don’t eat – their only purpose is to reproduce.

Random Cool Fact: Moth and butterfly wings are covered in thousands of wing scales, essentially flattened versions of insect hair. (Lepidoptera means “scaly winged.”). Lower inset photograph shows a close-up of the wing scales in a Luna moth eyespot.

Monarch, Danaus plexippus

Description: Look for these tiger-striped caterpillars on milkweed; the orange butterfly features a classic black-vein and white-dot pattern. Wingspan: 3½–4½ inch.

Ecology: Each fall, Northeastern monarchs undertake an epic migration south, where the entire population winters in a relatively small patch of forest in south-central Mexico. In spring, they move north, laying eggs and dying as they go. The monarchs you see this summer in northern Maine could be the fourth generation offspring of the monarch that flew south to Mexico last fall. All of this suggests that there must be a genetic component to the migration, since no individual butterfly makes the journey twice.

Random Cool Fact: The migration story wasn’t cool enough for you? OK, how about the fact that caterpillars sequester cardiac glycosides (i.e., poison) from the milkweed leaves they eat, concentrate it, and carry it forward into their chrysalis and adult stages. This makes them unpalatable to most birds.

Mourning Cloak, Nymphalis antiopa

Description: This spiny, black-and-red caterpillar cannot be confused with any other. When you see it, don’t touch it; the hairs break and release noxious chemicals that can cause nasty rashes. Butterflies have a wingspan of around 3 inches and are almost always the first butterflies encountered each spring.

Ecology: Caterpillars stay together upon hatching and can defoliate whole branches of poplar or willow trees. Butterflies go through a period of dormancy in summer, then re-emerge briefly in fall before finding a comfortable spot and hibernating through winter. In spring, look for them sipping sap at sapsucker holes.

Random Cool Fact: Mourning cloaks are our longest-lived butterfly – some individuals survive a whole year.

Eastern Tiger Swallowtail, Papilio glaucus

Description: Newly hatched eastern tiger swallowtail caterpillars are bird-dropping mimics. The last larval stage, seen here, has smallish eyespots that make it look like a tiny, nearsighted snake. Butterflies have 4½ inch wingspans and vary in color. Females can be yellow, like the one pictured here, but there’s also a black color phase.

Ecology: Caterpillars feed on black cherry, birch, ash, willow, cottonwood, and tuliptree. Butterflies take nectar and are often found in edge habitat, especially swamp edges.

Random Cool Fact: Eastern tiger swallowtails butterflies, and many other butterfly species, are often seen congregating at puddles on dirt roads. What they’re doing is eating the salt and minerals that have dissolved in the water. If there are no puddles, they still may gather on open dirt to regurgitate into the soil and slurp up nutrients this way.

White-Marked Tussock Moth, Orygia leucostigma

Description: The caterpillar is 1–1½ inches long, with a bright red head and four white to yellowish brush-like tufts of hairs on the back. Female moths, like the one pictured here, are wingless and therefore flightless. Males are medium-sized brown moths with a single dot on the forewing.

Ecology: One of our most ubiquitous caterpillars, the white-marked tussock could turn up on virtually any plant in the Northeast. A member of the Arctiidae family.

Random Cool Fact: Some male Arctiid moths sequester pyrrolizidine alkaloids (PA) from plants and use them as a defense mechanism. They can then sexually transmit this protection to a female mate. One study showed that a PA-deficient female becomes unpalatable to spiders almost immediately after copulation and that this unpalatability endures throughout her life.

European Skipper, Thymelicus lineola

Description: Green caterpillar can be distinguished from other grass skippers by the whitish lines that run the length of the body. Tiny orange butterflies are found in orchards and unmowed hay fields.

Ecology: European skippers overwinter as eggs. Caterpillars are private, feeding at night and sleeping through the day in silken leaf shelters. Butterfly is one of the most common in the Northeast.

Isabella Tiger Moth, Pyrrharctia Isabella

Description: The woolly bear is a fuzzy, orange and black caterpillar that becomes a dull, yellow to orange moth with a fat, furry thorax and a small head.

Ecology: One of our most familiar caterpillars, woolly bears are renowned wanderers. They hatch from eggs in fall and are often seen crossing roads, a strange fact, considering they eat almost everything. Look for them overwintering in your wood pile. In spring, they gorge themselves, then molt into Isabella tiger moths.

Snowberry Clearwing, Hemaris diffinis

Description: Simple, run-of-the-mill caterpillar becomes one of the Northeast’s most striking moths. Moths have fat, furry bodies and wings with clear windows in them (wingspan equals 1½–2 inches). They’re fast-moving and hover at flowers; as such, they’re often mistaken for tiny hummingbirds or giant bumblebees.

Ecology: Caterpillars feed on hawthorn, honeysuckle, snowberry, and viburnum. Moths like phlox, buddleia, and deep-throated flowers.

Gerry Lemmo is a professional freelance photographer from Warren County, New York. As a teenager, he was a member of the entomological club at the American Museum of Natural History.

That ‘parsley worm’ is really a caterpillar

If you grow parsley, dill, fennel or other members of the same plant family, you may come across a distinctive caterpillar feasting on the foliage.

Though often known as a “parsley worm,” this caterpillar is not a worm at all. Instead, it’s the larvae of a native butterfly called the Eastern black swallowtail.

The Eastern black swallowtail (Papilio polyxenes asterius) is one of the most common butterflies here in Western Pennsylvania. Their black wings spread 2 to 3 inches wide, and they’re often found nectaring on zinnias, coneflowers, phlox and many other garden plants.

When their wings are open, the females have pale yellow spots on the edges of their black wings and light blue at the base of their hind wings. You’ll also find a small, orange eye-spot at the base of the wings, just above the black “tail” that extends from the base of each hind wing. Females are typically a bit larger than males.

Male black swallowtails have a large yellow band across the middle of the wings and the blue coloration and eye-spot are less pronounced. They also have black “tails” extending from the base of each hind wing.

This butterfly is found across southern Canada and most of the eastern and mid-western U.S. all the way west to the Rocky Mountains.

The larval stage of the Eastern black swallowtail feeds exclusively on members of the carrot family (Apiaceae) such as those mentioned above.

Females lay eggs singly on host plants, and upon hatching the caterpillars are very tiny. They start out black with a white saddle and small orange spots. As they mature through several instars (life-stages) over the course of 15 to 30 days, the caterpillars change to a bright green with black and white stripes and rows of yellow dots. This is the stage at which most gardeners notice them munching on their plants. But, by the time the caterpillars reach this stage, they’re almost done feeding and ready to pupate. If you find any on your plants, please don’t disturb them.

When the caterpillars are ready to pupate, they often crawl off of host plants to look for a safe place to build their chrysalis. They position themselves along a plant stem, head up, and they produce two silken threads about a third of the way down their bodies. These threads hold them to the stem during pupation.

Eastern black swallowtail chrysalises are green with a tinge of yellow, and they’re hard to spot in the garden. As the pupae mature, they may or may not turn brown. The generation that overwinters in the garden as pupae are almost always brown. There are two to three generations of swallowtails per year here in Pennsylvania.

If you’d like to encourage this beautiful butterfly to take up residence in your garden, plant lots of their favorite caterpillar host plants, including caraway, celery, dill, parsley, fennel, zizia, and even Queen Anne’s lace. Also be sure to plant lots of nectar plants for the adults.

Another must-do for gardeners who want to encourage all butterflies, is allowing the garden to stand through the winter, rather than doing a fall cleanup. Because Eastern black swallowtails — and many other butterflies ­— overwinter in our gardens (monarchs are one of only a select few species that migrate away for the winter), it’s essential that we provide overwintering habitat for them in the form of standing perennial stems, ornamental grasses and leaf litter.

Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden: A Natural Approach to Pest Control” and “Good Bug, Bad Bug.” Her website is

Send your gardening or landscaping questions to [email protected] or The Good Earth, 622 Cabin Hill Drive, Greensburg, PA 15601.

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    Preventing Pests from Attacking Your Parsley

    Parsley is a strong plant that does not often suffer from insect infestations. Prevention is often more effective than resorting to chemical controls. The following will provide some tips to help you prevent pests from attacking your parsley.


    Parsley is a very strong growing plant and as long as it is healthy, it will resist most insect attacks. Keeping parsley healthy is all about keeping the soil in the best condition. Don’t use chemical fertilizers on your soil. These can add salt and drive away earthworms. Earthworms are vital to soil health because they help ventilate the soil by digging tunnels and the castings they leave behind are probably the most nutritious organic fertilizer available. Water your plants in the morning to reduce evaporation and to give the leaves time to dry to prevent molds growing. Healthy plants in healthy soil suffer less damage from insect attacks.

    Rust Fly

    The rust fly larvae attack the small, fibrous roots of plants and even tunnel into the larger roots. There is often little outward sign of an infestation until the plants start to die. Once the rust fly has become established, there is little chance of getting rid of it. Some damage can be avoided by planting late in the season, mid to late June, missing the first hatching of the adults.

    Infected plants should be destroyed immediately. You can cover your plants to prevent flies from laying their eggs on them.

    Parsley Worms

    Parsley worms are the caterpillars of the black swallowtail butterfly. Although the parsley worms can do enormous damage to plants, the butterflies are beautiful creatures. The caterpillars are large enough to be removed from the plants by hand so you can transfer them to plants that are not so valuable. If you keep a small patch of weeds in your garden, that would be an ideal location for them. If you want to keep some of the caterpillars, you can also sacrifice a few parsley plants.

    Spider Mites

    Spider mites are tiny spider-like creatures that feed on the soft skin of the plant leaves. Spider mites reproduce rapidly and in a rich food area, will soon become a major pest. Being so tiny, the damage of one spider mite is negligible, showing up as a small yellow spot. An attack by great numbers will leave the plants looking decidedly spotty. The only real protection against spider mites are spider mite predator bugs, which you can purchase. They work well on indoor infestations, but not so well on outdoor infestations.

    Parasitic Wasps

    Parasitic wasps feed upon all sorts of caterpillars. They are very tiny and kill off caterpillars by laying their eggs inside the body cavity. The larvae that hatch devour the caterpillar before it can pupate into a moth or butterfly to start the whole process over again. Dill attracts the parasitic wasp because the aroma it gives off will attract butterflies and caterpillars.

    Maintaining healthy plants in healthy soil is your first line of defense. Combined with predator bugs, this should be enough to keep your parsley safe and sound.

    Using Parsley For Butterflies: How To Attract Black Swallowtail Butterflies

    My parsley is attracting butterflies; what’s going on? Parsley is a familiar herb that makes an attractive garnish or provides a bit of flavor and nutrition to soups and other dishes. Parsley is easy to grow and the ruffled leaves add beauty and interest to the herb garden. This is probably old news, but what you may not know is that parsley is a butterfly-friendly plant, and is especially beneficial for attracting black swallowtails, anise swallowtails and others. Read on to learn about parsley attracting butterflies, and tips for growing parsley for butterflies.

    Eastern Black Swallowtail on Parsley

    Parsley is suitable for growing as a perennial in USDA plant hardiness zones 4 through 9. By planting parsley, you’re doing a huge favor for eastern black swallowtail butterflies, as this species feeds only on a few plants, including:

    • Dill
    • Parsley
    • Fennel
    • Carrots
    • Queen Anne’s lace

    Providing parsley for butterflies can create a home for a native population that you can observe throughout their lifetime.

    Eastern black swallowtails,

    appreciated for their delicate beauty, are recognizable by their black wings, each marked with two rows of bright yellow spots, which are larger and brighter in males. The spots are divided by powdery blue markings, which are more pronounced in females.

    Growing Parsley for Butterflies

    Although parsley grows in a variety of conditions, it performs best in full sunlight and relatively rich, well-drained soil. Plant seeds directly in the garden after all danger of frost has passed in spring, or start them indoors six to eight weeks before the last average frost date in your area. Cover the seeds with about 1/8 inch of soil or fine sand.

    Keep the soil slightly moist until the seeds germinate (be patient, as germination may be slow). Thereafter, water the plants deeply once a week. Thin the seedlings to a distance of 10 to 12 inches between each plant when the seedlings are 2 to 3 inches tall.

    How to Attract Black Swallowtail Butterflies

    If you’re serious about attracting black swallowtails and other butterflies to your garden, here are a few tips that will help.

    • Avoid insecticides and other chemicals.
    • Arrange a few flat stones in your garden. Butterflies need a place to rest and bask in the warmth of the sun.
    • Place a tray of wet sand near your herb garden. Butterflies use the damp sand for extracting minerals and drinking water. Remember to keep the sand moist.

    Will Caterpillars on Parsley Hurt Plants?

    If you want to attract black swallowtails, don’t destroy the beautiful, brightly striped caterpillars! The butterflies lay their eggs on the parsley plants, which hatch into caterpillars. The caterpillars munch on leaves before pupating and creating a chrysalis.

    When the cocoon matures, it splits and releases a beautiful black swallowtail butterfly. The butterfly depends on the plant, but the plant won’t suffer.

    A Photo Journey Raising Eastern Black Swallowtails from Egg through Butterhood

    When we first started the butterfly garden, I believed that eastern black swallowtails were regular visitors to our Minnesota butterfly garden. But after years of research and networking with other butterfly enthusiasts, I realized this was not the case.

    A bird’s eye view of the abdomen distinguishes a true black swallowtail from its close relatives…

    Don’t be Tricked by a Tiger

    Eastern Black Swallowtails (Papilio polyxenes) are one of the most abundant swallowtail species across North America. to see if they’ve been sighted in your region?

    Common host plants include common rue, curly parsley, carrot tops, golden Alexander, bronze smokey fennel, dill, celery, asparagus, and Queen Anne’s Lace.

    In our garden, we’ve had the most success attracting them with fennel, but we stopped planting it because it attracted too many wasps. Wasps are beneficial pollinators, but in large numbers they can wreak havoc on the caterpillar population in your garden. Currently, we have rue and Golden Alexander.

    If you’re interested in learning more about (or purchasing) black swallowtail host plants, get more info on my butterfly plants page

    The Eggs

    One of the pros of fennel is that it contrasts beautifully with black swallowtail eggs to make finding them easy, considering their small size…

    Glowing Needle in a Haystack

    Unlike monarchs, eastern black swallowtails will often lay eggs on the tops of leaves, which can make them a little easier to find. However, they tend to blend in with their host plants.

    The Caterpillars

    Our most recent black swallowtails were brought in as small caterpillars. I was not expecting to find them on our golden Alexander plant, but they were easy to see against contrasting yellow blooms. So, we took stem cuttings (with caterpillars) and placed them in floral tubes.

    Tube Tip: take long cuttings so that the stem goes to the bottom of your floral tubes. That way you’ll have to refill less often.

    Find Floral Tubes on the Raising Resources Page

    A Golden Opportunity

    Common rue is also easy to use with floral tubes and is also a host plant for Giant Swallowtail Butterflies.

    Some people have allergic reactions to rue so you may want to handle this plant with gloves.

    A Host Plant for TWO Swallowtail Species

    Fennel is a top host plant for attracting eastern black swallowtails and the feathery foliage is beautiful addition to the garden landscape…

    Other host plants for black swallowtails include curly parsley, dill, and carrot tops.

    Monarchs go through their metamorphosis almost twice as quickly as their swallow mates. I’m often asked if they can be raised in the same enclosure. I’m not aware of any disease or in-fighting issues, but I’d suggest raising them on elevated stem cuttings to keep them separated. We also use separate mesh enclosures, but did introduce these two briefly:

    I’m not too sure about this parsley?!

    As eastern black swallowtails grow, they also became more colorful. Many confuse monarch caterpillars with black swallowtails, but if you compare the caterpillars below, with the large monarch above, you can see the differences.

    We’re Golden

    Also, monarchs only eat milkweed so you’ll never seem them feasting on your dill or fennel…or zizia!

    Once the caterpillars are ready for the next stage, they are kind enough to let you know in advance 💩 😉

    The Chrysalides (or Chrysalises)

    Before the caterpillar searches for that perfect spot to form its chrysalis, it will purge any remaining food all over the cage floor. Thankfully, we had our poo poo platter inserted on the cage floor so they purged inside that. Otherwise, it can stain the cage floor, as our eastern tiger swallowtails did multiple times in this cage:


    Swallowtails will attach themselves to the cage wall, cage ceiling, stick, or host plant in two places: at the base with a silk pad and with a silk girdle around the mid section of the caterpillar:

    Not Looking So Good

    So it looks like we’re good to go? Not so fast…

    This poor swallowtail was compromised by disease or parasites. This photo was taken several seasons ago, and the caterpillar never did form its chrysalis. We’ve never had any diseases (I’m aware of) affect swallowtails. However, we’ve had caterpillars parasitized by the Trogus Pennator Wasp. If you know what happened to the caterpillar pictured above, please post a comment a the bottom of the page…

    Here’s a healthy eastern black swallowtail, to take us to the next stage of the butterfly life cycle:


    This caterpillar formed a chrysalis directly on its golden Alexander host plant. Green chrysalides are more common during the spring and early summer. Many believe this is a defense mechanism against predators that helps them blend in with their surroundings…

    In the late summer and fall, the chrysalis colors are more likely to blend in with the tree branches that will hide them from predators over winter.

    A monarch chrysalis will hatch reliably in 7-10 days, but the swallowtail family is on a European vacation schedule. They can take 2-3 weeks, or longer if they see fit. If you’re raising toward the end of the season, they may even decide to overwinter until next season.

    The Butterflies

    Before your butterfly emerges, the chrysalis will turn dark (with yellow accent spots) revealing the butterfly inside. It’s easy notice this change with a green chrysalis, but the change is more subtle when the chrysalis is formed brown.

    When the adult butterfly emerges, it will come out of the top of the chrysalis, and find a place to hang down to expand and dry its wings properly:

    Drying Off

    As with monarchs, I suggest placing eastern black swallowtail butterflies outside in a closed mesh cage for a couple hours to sunergize 🌞 them. This insures they will have plenty of energy to elude potential predators upon release.

    Females typically have more blue hue in their hindwings, and less prominent yellow wing markings:

    Males typically have less blue hue in their hindwings, and more prominent yellow wing markings:

    Eastern black swallowtails don’t spend as much time in the butterfly garden as some others in the swallowtail family, but zinnias and obedient plant are two plants they have favored in our northern garden over the years. If you know of other BST favorite nectar plants, please leave a comment below…

    Black Beauty in the Butterfly Garden Would you like to start raising butterflies in 2018? for butterfly cages and helpful raising supplies.

    Please Post Questions, Comments, or Share your Experience Raising Eastern Black Swallowtail Butterflies.

    Share the Joy of Butterflies

    • The Black Swallowtail is Swallow(tail)ing My Life

      I’d like to share with you a mild obsession with which I am currently spending a ridiculous amount of my time and grocery budget. This new hobby is raising black swallowtail caterpillars.

      I started last summer, right after I got back from my honeymoon, when I noticed that my parsley plant was half missing. I assumed rabbits or deer were getting bold enough to come up onto my stoop, because the parsley was being reduced to stems overnight. Imagine my surprise when, instead, I find two fat little caterpillars.

      Meet said fat caterpillars

      Instead of leaving them outside to let nature take its course, I stuck them in a jar, because I am apparently five years old. I thought they might be monarchs because of the bright green color, but I apparently do not remember at all what a monarch caterpillar looks like. Five minutes of Googling told me that they were actually Eastern Black Swallowtail larva. (Or, ‘caterpillars’ for you non-weekend-entomologists like me.) I recommend this resource if you find yourself with a caterpillar and feel compelled to help it fend off death.

      Just Call Me Daenerys Yarnborn, Mother of Several Black Swallowtail Larva

      I learned very quickly that the caterpillars I adopted were at the stage of their development where they eat parsley like the world is about to end. You guys, these things love parsley more than I will ever love anything in my entire life. I mean, they were preparing to tether themselves to a stick and turn into a soup just hoping they would wake up as a butterfly and not a bird snack, so maybe that’s fair. But I ran out of parsley very quickly.

      I made my husband drive me to the store at 10 pm to buy organic parsley. It had to be organic because the regular kind might have residues of pesticides on it, and I was currently trying to help the pests win the war against the American farmer. My bugs were now eating better produce than I feed my family, and this was potentially a low point for me. But lower points were yet to come.

      The Anticipation of Watching Bug Soup

      It doesn’t look like it, but this is bug soup

      When black swallowtail caterpillars get ready to pupate, they spin themselves a little tether out of silk and anchor themselves to a twig to wait out their awkward adolescence. They look just like little contractors climbing a Verizon cell tower. During this chrysalis phase, the caterpillar inside literally turns into soup. Somehow, this goo rearranges itself into a goddamn butterfly, and that is a goddamn miracle.

      Pictured, a goddamn miracle

      I had a nice time hanging out on my porch while the butterfly dried out its wings while perched on my finger. When it was ready to leave and flapped away for the first time, I fucking cried. I felt like I had just watched my kid leave for college. I wasn’t really wrong, in that my black swallowtail was off to sip nectar like it was going out of style and find herself some sexy man butterfly ass.

      Imagine my wonderment, my sense of awe at the beauty and majesty of the perfection of creation, when I saw a black swallowtail return to my stoop a few days later, and lay eggs on my parsley plant.

      It was a miracle. It was magical. I was up to my elbows in fucking caterpillars.

      holy shit that’s a lot of black swallowtail caterpillars

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      I never bothered removing all 32 of these guys from the host plant, but just brought the whole damn thing into the kitchen. Thing were going well and they were growing like little weeds, until they reached that time in a young caterpillar’s life when thoughts turn to wandering in search of a place to pupate. Having 32 black swallowtail caterpillars crawling all over his kitchen is I think to this day the closest my husband has ever come to asking for a divorce.

      Putting them back outside to let them pupate in the wild was an act of faith and relinquishing of control, a Jesus Take the Wheel moment if you will. At least that’s what my therapist told me. All I know is that I watched the local cardinal population treat my precious little babies like parsley flavored Fruit Gushers while they were helpless and waiting to turn into butterflies.

      So, after that experience in existential horror and trauma, I thought my black swallowtail raising days were over… until this year.

      That is a baby black swallowtail caterpillar emerging from its egg.

      This is six black swallowtail caterpillars taking residence in my house and eating the only organic produce that I have ever bothered to buy.

      And that is a black swallowtail chilling on my face. Raising butterflies is awesome, you guys.

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      This saga began several months ago, when the adult black swallowtail butterfly emerged from a chrysalis that had survived the chill of winter. Nectar and pollen from a variety of flowers sustain the butterfly in spring and summer. After mating, the female swallowtail searches for wild plants in the carrot family such as Queen Anne’s lace or cultivated delicacies including carrot, fennel, dill, and parsley. She lays a few eggs on a plant and in a matter of days these hatch into tiny caterpillars. At first, tiny black swallowtail caterpillars resemble bird droppings. As with other swallowtails we visited in previous episodes like the spicebush swallowtail, this scam may help these tiny tasty treats escape detection and death at the beaks of would-be predators like birds.

      Older black swallowtail caterpillars are banded with dazzling swatches of black and yellow on a field of green. These creatures do not attempt to blend in with their surroundings. Older stages of black swallowtail caterpillars have their own clever defense to ward off enemies intent on making them a meal. Just behind the head of the caterpillar is a specialized structure called the osmeterium. While chillin’, this forked, orange appendage is tucked beneath the skin out of sight. But when the swallowtail larva is threatened, it extends the osmeterium in the direction of the disturbance. This glandular organ is coated with foul smelling chemicals, isobutyric and methylbutyric acids, with a fragrance of rancid butter. The disturbing visual and olfactory display discourages hungry predators from wanting to dine on this beautiful caterpillar. In addition to the stinky fluid from the osmeterium, the caterpillar will often disgorge its last meal to help repel an attacker.

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      Female Black Swallowtail Butterfly
      on Milkweed

      Raising a Black Swallowtail butterfly indoors is fun, easy, and educational. Black Swallowtail butterflies are great to raise indoors for several reasons including abundance, plentiful food source, attractive and interesting caterpillars, and of course beautiful butterflies.

      The Black Swallowtail can be found anywhere East of the Continental Divide in America. The Anise Swallowtail is the Western version of this butterfly and is surprisingly different in appearance considering the caterpillars and chrysalises are nearly identical.

      The host plants of the Black Swallowtail butterfly include such plants as carrots, parsley, dill, fennel, Queen Anne’s Lace and rue. The Anise Swallowtail caterpillar feeds on anise as well and reportedly citrus plants also. Many of these plants can be found relatively easily in garden centers and nurseries around the country. That makes it easy to find host plants to plant and to get more food for your caterpillars if you find yourself running low. However, there is a risk that the growers used pesticide on the plants which will kill the caterpillars. Ask before you buy and be sure to clean (rinse) the vegetation once you get it home. It’s always best to grow your own if you can but that is not always practical for everyone.

      Although it is not generally recommended, I have always had success using parsley from the grocery store in a bind. This is a bit risky because, again, it is unknown how that parsley was grown. It may have pesticides on it. I have rinsed it thoroughly and it has worked for me. Personally, I feel that if it kills my caterpillars then I’m not so sure my family should be eating it either and I would definitely let the grocery store know about it!

      Once you figure out what host plant does best in your area, be sure to plant a bunch of it in the spring/summer to attract egg-laying butterflies. Parsley has worked well in my area in the Southeast where as Dill has not been so great because it just seems to dry up too early before the end of summer. My favorite (and the butterflies favorite) is the rue plant as a host because it is an attractive and reliable perennial and is also a host plant for Giant Swallowtails.

      Also, planting nectar plants will help to attract butterflies. Butterflies get their food from the nectar in flowers. Black Swallowtails are reported to especially like Milkweed, Phlox, Red clover and Thistle. In my yard I have seen them on Homestead Purple Verbena quite often and they love my Zinnias as well as the Milkweed family of plants.

      Finding butterfly eggs of the Black Swallowtail is not too hard. In my experience Black Swallowtail eggs are usually found on the top of leaves. The eggs are tiny white/yellow spheres (there are several pictures in the Butterfly Egg Photos section of this website). You can bring the eggs inside on the leaves or wait until the caterpillars hatch out and grow a little. If the eggs are laid on a potted plant you may want to bring the whole pot inside. If the eggs are on a plant in the ground you can bring some cuttings in or wait.

      The caterpillar will change a lot in appearance as it grows. When it is young it is black with a white stripe in the center. Shortly before it pupates it will look like the pictures below. Even as an adult caterpillar they can vary in coloration. They are all striped but some have alot of white, others have much more green and some are very dark looking with a lot of black. They have all turned into healthy butterflies.

      Don’t wait too long to bring them in or you will start losing caterpillars to their natural predators. Depending on how many caterpillars I already have indoors (and how much food I have) I sometimes only bring a few in and leave the rest outside to fend for themselves. Usually their numbers dwindle rather quickly. It is estimated that only 1 out of every 100 eggs laid will make it to a butterfly.

      We have used both an open and enclosed caterpillar home for Black Swallowtails. However, the Black Swallowtail caterpillar loves to roam right before it gets ready to pupate so you may want to keep these caterpillars enclosed as they grow or just enclose them once they start to get big. Enclosed is much easier but I invite you to read our article about indoor caterpillar homes for more information including the plusses and minuses.

      When the caterpillar reaches the size of about 1.5 inches (or about the size of the caterpillar pictured on my daughter’s hand) it will be ready to pupate. Also, these caterpillars make a dime-to-quarter size green mess as they purge undigested food shortly before pupating so if they are not enclosed you may want to put some newspaper under the caterpillars home.

      Black Swallowtail Caterpillar Showing Osmeterium

      Another interesting note about this caterpillar is the osmeterium (harmless to humans). It is probably the only possible negative (if it even is a negative) to raising any of the swallowtail caterpillars indoors, but it is such an oddity that the interest overcomes the negativeness. The osmeterium is shaped like a two prong fork that is right behind the caterpillars head. The osmeterium of the Black Swallowtail caterpillar is bright orange and pops up to let out an unpleasant smell when the caterpillar is touched or disturbed.

      My children get a kick out of touching the caterpillar and watching the osmeterium pop out then disappear again. The smell has been described to be foul or like rotten cheese. It is certainly not pleasant but not intolerable either. I encourage them to only do it with the outdoor caterpillars and to wash their stinky hands when they are done!

      One more note about the Black Swallowtail caterpillar: it is safe to humans to hold and touch the caterpillar. It is not always safe for the caterpillar, however. The smaller they are, the more delicate they are. Also, they will molt as they grow (see life cycle of a butterfly for more information). When they get ready to molt they will stop eating and stay still for around 24 hours then crawl out of their old skin. During this time they are delicate and should not be moved.

      Black Swallowtail Caterpillar
      Ready to Pupate

      When the caterpillar gets ready to pupate it will scrunch up along a stick or stem and then spin its silk. It will attach itself to the stem/stick like a telephone lineman hangs on a pole with a belt. The caterpillar will use a belt of silk as well as attach its base to a patch of silk.

      Brown form of a Black Swallowtail Butterfly Chrysalis

      When it is ready, (about 24 hours after attaching) it will wriggle its outer skin off exposing the chrysalis beneath. The chrysalis will either be green or brown depending on the color of the surrounding area.

      In 1-2 weeks the butterfly will emerge. This usually happens in the morning hours after the sun has come up but I’ve had just a few come out in the early afternoon also. The butterfly has to be able to hang with its wings down (see life cycle of a butterfly for more information) so if some sticks or leaves are close to the chrysalis then you may want to clear them before the butterfly comes out.

      After several hours the butterfly will be ready to fly away. Often times when they get close to being ready and start fluttering we will carry them outside on a stick (or my kids love to have the butterfly hold onto their fingers). If they are not quite ready for flight we will put them on a stick in a pot or on a plant in the sun where they can finish.

      Male Black Swallowtail

      Black Swallowtail butterflies overwinter in the chrysalis. So, if your chrysalis does not form until late summer then it may not come out of the chrysalis until the following spring. To read more about this please visit How to Overwinter a Chrysalis.

      There are many different ways to raise a Black Swallowtail butterfly. You have choices in type of indoor caterpillar housing, whether you start with an egg or caterpillar, how you feed them (potted plant or cuttings) and how/when you release them. This article shares our experiences with Black Swallowtail butterflies but many different methods will work. Once you give it a try you will find what works best for you. It is truly a spectacular experience and I hope you enjoy it as much as we do.

      Plant a little extra parsley to help support swallowtails in the garden

      Question: Last summer, my parsley plants were inundated with caterpillars for about two weeks. Then they went away. The caterpillars were green and black striped with yellow dots. Were they monarch butterfly caterpillars? Or were they some kind of pest?

      Answer: The insects you describe are often called parsley worms, though they are not worms at all; they’re caterpillars. Parsley worms are the larval stage of the Eastern black swallowtail butterfly ( Papilio polyxenes asterius). These butterflies are quite common in our area, and their caterpillars feed on many different species of plants in the carrot family ( Apiaceae), including parsley, parsnips, caraway, fennel and dill.

      The wings of adult butterflies are black with two rows of yellow spots and light blue markings, though the blue on the males is much less prominent than on the females. Both male and female Eastern black swallowtails have an extension, or “tail,” that projects out of the base of their wings. The adults feed on the nectar of many different flowering plants.

      Female butterflies lay tiny, cream-colored eggs on host plants throughout the summer. When the caterpillars first hatch, they’re very small and mostly black with a white saddle across their mid-section and tiny orange spots. As they mature, the caterpillars develop their distinct coloration. The caterpillar stage lasts between two weeks and a month, depending on the weather conditions and other factors.

      Full-grown larvae are light green and black striped with yellow spots, and they’re about as big as your pinky finger.

      The caterpillars pupate in a green or brown chrysalis that’s anchored to a plant stem or other structure with two white, silken threads. They spend one to two weeks in pupation before emerging as an adult butterfly. There are two generations throughout the summer, and the final generation spends the entire winter in pupation.

      As an interesting project, you can carefully collect a full-grown parsley worm and rear it in a large, glass Mason jar with holes cut into the lid. Feed it leaves from the host plant on which you found it, and place a stick diagonally inside the jar. The caterpillar will enter pupation and form its chrysalis on the stick. Watch the jar very carefully because about two weeks later, the butterfly will emerge. After its wings have fully expanded soon after emergence, take the jar out into the garden and release the butterfly. It’s a pretty amazing thing to watch.

      Though parsley worms sometimes feed on desirable garden plants, they aren’t generally considered to be pests. Their feeding seldom causes anything more than superficial damage to the plants, which quickly rebound when the caterpillars go into pupation. If you’re worried about them consuming more than their fair share of parsley, dill and other host plants, just plant a few extra plants next year. That way, they’ll be more than enough to go around.

      If the caterpillars were those of a monarch, they would be found on milkweed plants, rather than on members of the carrot family. Monarch butterflies can only use species of milkweed as host plants for their young. In fact, the vast majority of butterflies are host-exclusive, feeding only on one particular group or species of plants as larvae. Monarch caterpillars also are striped, though their stripes are black, white and yellow.

      Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden: A Natural Approach to Pest Control” and “Good Bug, Bad Bug.” Her website is

      Send your gardening or landscaping questions to [email protected] or The Good Earth, 503 Martindale St., Third Floor, D.L. Clark Building, Pittsburgh, PA 15212.

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