Papilio polyxenes facts for kids
Quick facts for kids Black swallowtail |
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Scientific classification  |
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| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Lepidoptera |
| Family: | Papilionidae |
| Genus: | Papilio |
| Species: |
P. polyxenes
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| Binomial name | |
| Papilio polyxenes Fabricius, 1775
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The black swallowtail (Papilio polyxenes) is an amazing North American butterfly. It is also called the American swallowtail or parsnip swallowtail. You can spot this colorful insect dancing over garden flowers and sunny fields. The species was named after Polyxena, a royal princess in ancient Greek mythology. Her father was King Priam of the legendary city called Troy. Its chubby green caterpillar often eats garden herbs like garden parsley. Because of this favorite food, backyard gardeners often call the caterpillar the "parsleyworm."
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A very similar insect named Papilio joanae lives in the rugged Ozark Mountains. However, science shows that species is actually closer to Papilio machaon. In nature, adult black swallowtails practice polyandry when selecting their mates. Males gather at high landmarks during a special contest called lek mating. The father butterflies provide no care for the eggs after mating takes place. Instead, hardworking females inspect these display areas to select healthy mates.
Contents
- All About the Black Swallowtail Butterfly Family
- Habitat and Where Black Swallowtail Butterflies Live
- Butterfly Anatomy and How Caterpillars Grow
- Clever Mimicry and Staying Safe from Predators
- The Life Cycle of a Black Swallowtail Butterfly
- Delicious Host Plants for Hungry Parsleyworms
- Daily Habits and Butterfly Behaviors
- Mating Systems and How Swallowtails Choose Partners
- Similar Swallowtail Species in North America
- Images for kids
All About the Black Swallowtail Butterfly Family
Scientists place Papilio polyxenes inside an insect group known as the tribe Papilionini. This tribe belongs to the worldwide swallowtail family known to science as Papilionidae. Every member of this group has tiny extensions on their hindwings called tails. These swallow-like tails give the whole butterfly family its common name.
The black swallowtail belongs to the famous genus called Papilio. This genus is the largest branch within the entire swallowtail family. One special island subspecies called polyxenes lived in Cuba, but scientists consider it extinct. Caterpillars in this insect group usually feast upon three key plant families. They love citrus leaves in Rutaceae and spicy laurel leaves in Lauraceae. However, this swallowtail especially favors fragrant wild plants from the family Umbelliferae.
Habitat and Where Black Swallowtail Butterflies Live
Papilio polyxenes lives across a massive geographic range stretching over two big continents. They range from southern regions of Canada all the way down to South America. Within North America, they are far more common east of the Rocky Mountains.
These butterflies love bright, open areas where sunshine warms their wings quickly. You can discover them gliding across farm pastures, town parks, wet marshes, and deserts. They flourish in both warm tropical regions and pleasant temperate habitats with four seasons. They avoid deep, dark woods because they need bright sunlight to stay warm.
Butterfly Anatomy and How Caterpillars Grow
Every black swallowtail transforms through complete metamorphosis during its exciting insect life. Their bodies change completely as they grow from tiny eggs to flying adults.
Eggs and larvae
A mother butterfly carefully deposits tiny, spherical eggs on healthy green leaves. These smooth eggs start out with a pale yellow color. Tiny baby larvae chew their way out of the eggshells a week later.
Very young larvae are mostly black with white spots and a white saddle. This clever pattern looks just like a splash of messy bird droppings. Hungry birds ignore the young caterpillar because it looks like unappealing bird waste. As it grows, the older caterpillar turns bright green with bold black stripes. Each dark band features bright yellow or orange spots along its plump sides.
Caterpillar and chrysalis
The growing caterpillar eats plants that contain bitter organic chemicals called plant toxins. It safely stores these chemicals so that it tastes terrible to hungry birds. If a predator attacks, the caterpillar shoots out an orange organ called an osmeterium.
This hidden gland looks just like the forked tongue of an angry snake. It quickly pushes out from right behind the caterpillar's soft green head. The organ releases a foul, stinky odor that drives hungry ants and birds away. Once the threat leaves, the caterpillar pulls the smelly organ back inside.
When fully grown, the larva forms a protective shell called a pupa. Inside this case, also called a chrysalis, the insect rebuilds its body. The shell can be bright leaf green or dull wood brown.
The color is controlled by genetics, helping the insect match its chosen resting spot. Green cases often turn very dark green right before the butterfly breaks out. The caterpillar spins a strong silk button and a silk safety girdle loop. This loop holds the pupa upright so the new butterfly can unfold its wings.
Sexual dimorphism
Adult black swallowtails show clear visual differences between boys and girls, called sexual dimorphism. Their wingspan measures between 6.9 and 8.4 centimeters wide across the wing tips. Female swallowtails are usually slightly larger than the males flying around them.
The upper wing surface displays a dark velvety black background with yellow markings. Male wings display two bright rows of large, bold yellow spots. Females have much smaller yellow spots, but show an extra band of metallic blue. This blue dusting helps female butterflies look like another bad-tasting insect through Batesian mimicry.
Both sexes feature an orange-red spot with a black pupil on their wings. This eye-spot pattern looks like a bullseye near the bottom edge of each hindwing. The underside or ventral wing surface looks almost identical on both male and female butterflies. The front wings display yellow spots, while the hindwings show bright orange rings. These fiery orange spots are separated by soft patches of powdery blue scales.
Clever Mimicry and Staying Safe from Predators
Birds love to hunt juicy insects, so butterflies need clever defenses to survive. The black swallowtail avoids hungry predators by copying an insect that birds avoid eating.
The female mimics a poisonous woodland butterfly called the pipevine swallowtail, or Battus philenor. Pipevine caterpillars eat toxic vines, making the adult butterflies taste completely sickening to birds. Hungry birds quickly learn to avoid any dark butterfly showing glowing blue wing patches. The female black swallowtail borrows this protective look through dorsal mimicry.
Females spend lots of daytime hours hovering openly over leaves to lay eggs. Flying out in the open makes them easy targets for sharp bird eyes. Looking like a toxic pipevine swallowtail keeps the egg-laying mother safe from attacks. Underneath, both males and females share the same bright orange and blue dots. This underside pattern also mimics B. philenor, protecting resting swallowtails when their wings fold together.
Intrasexual selection
Sometimes a male black swallowtail develops wing patterns that look like a female. This unusual pattern gives the male extra protection from birds while feeding on flowers. However, looking like a female causes major problems when competing against other rival males.
Normal-patterned males win far more territory battles during fierce intrasexual competition. Females do not care whether a male has normal or female-like wing patterns. They happily mate with either color pattern as long as he holds territory. Because males must fight rivals, male-male intrasexual selection keeps the classic yellow pattern strong. A male needs bright yellow spots to warn other males away from his perch.
The Life Cycle of a Black Swallowtail Butterfly
The life of a black swallowtail begins when a mother finds a plant. She glues single eggs one at a time on tender young plant leaves. An egg hatches after four to nine days of warm summer weather.
The tiny caterpillar feeds constantly for ten to thirty days as a larva. During this feeding period, the caterpillar sheds its tight skin five different times. Each distinct growth stage between skin sheds is known to science as an instar. When ready, the caterpillar forms a chrysalis, which lasts about eighteen days in summer.
Famous insect researchers studied swallowtail survival rates around open fields near Ithaca, New York. They found that caterpillars on wild herbs like wild carrot survived best. Caterpillars living on sweet wild parsnip plants also grew strong and healthy. However, eggs laid upon dangerous poison hemlock plants rarely survived to the final fifth instar.
The scientists noticed that caterpillars living on hills survived much better than valley caterpillars. Caterpillars placed 300 to 435 meters above sea level avoided ground-crawling predators. In low valleys at 120 meters elevation, hungry predators ate far more eggs.
Emergence
When autumn arrives, the late summer caterpillars pupate inside their tough silk-girdled shells. Instead of hatching, the pupa enters a resting sleep to survive freezing winter cold.
When warm spring sunshine warms the land, adult butterflies break free from their cases. Adults crawl out during the morning hours so their wings dry in sunlight. The first seasonal group of flying adults fills the sky from May through June. Their offspring form a second flying group that takes wing during July and August. In warm southern areas, a third brood may emerge before cold weather arrives.
Life expectancy
Black swallowtail butterflies live longer lives than many other temperate butterfly species. They fly with incredible speed and can dodge snapping birds with acrobatic loops.
However, bad weather like heavy rain and sudden freezing nights can harm them. Butterflies cannot fly when their flight muscles become too cold to flap properly. If bad weather lasts for days, butterflies starve and become easy meals for predators. At night, swallowtails roost upside down under wide leaves to hide from hunting mice.
Delicious Host Plants for Hungry Parsleyworms
Mother butterflies search for specific garden plants belonging to the wild carrot family, or Apiaceae. A female uses her sensitive eyes and chemical sensors on her feet.
Her antennae detect fragrant plant smells before she drops down toward the stems. These landing instincts are completely natural and are hardwired into her brain from birth. An adult butterfly does not prefer the specific plant she ate as a caterpillar.
Females choose from many delicious herbs and wild flowers when preparing for oviposition:
- American angelica, known in botany as Angelica atropurpurea
- Hairy angelica, known in botany as Angelica venenosa
- Fresh green Dill, known in botany as Anethum graveolens
- Cutleaf waterparsnip, known in botany as Berula erecta
- Spotted water hemlock, known in botany as Cicuta maculata
- Canadian honewort, known in botany as Cryptotaenia canadensis
- Queen Anne's lace, known in botany as Daucus carota
- Rare wedgeleaf eryngo, known in botany as Eryngium cuneifolium
- Garden Fennel, known in botany as Foeniculum vulgare
- Tall cow parsnip, known in botany as Heracleum maximum
- Fragrant Lovage, known in botany as Levisticum officinale
- Cucumber magnolia, known in botany as Magnolia acuminata
- Sweetbay magnolia, known in botany as Magnolia virginiana
- Sweet cicely, known in botany as Osmorhiza claytonii
- Long-styled sweet cicely, known in botany as Osmorhiza longistylis
- Endangered Canby's dropwort, known in botany as Oxypolis canbyi
- Slender water cowbane, known in botany as Oxypolis filiformis
- Garden Parsnip, known in botany as Pastinaca sativa
- Fresh green Parsley, known in botany as Petroselinum crispum
- Slender Mock bishopweed, known in botany as Ptilimnium capillaceum
- Herb-of-grace or common rue, known in botany as Ruta graveolens
- Hemlock water parsnip, known in botany as Sium suave
- Roughfruit scaleseed, known in botany as Spermolepis divaricata
- Yellow pimpernel, known in botany as Taenidia integerrima
- Prickly ash shrub, known in botany as Zanthoxylum americanum
- Golden alexanders, known in botany as Zizia
Daily Habits and Butterfly Behaviors
Butterflies are cold-blooded creatures, meaning their environment controls their body heat. They must use smart behaviors to stay warm and active each day.
Thermoregulation
To take off and glide smoothly, a butterfly needs warm muscles inside its chest. Its core chest area, called the thoracic region, must reach about 24 degrees Celsius.
To warm up on chilly mornings, the butterfly tilts its wings toward the sun. It perches low near warm rocks and lifts its abdomen above flat wings. On blistering hot summer afternoons, the butterfly seeks cool shade to avoid overheating dangerously. It drops its body beneath its wings and perches much higher off the ground. When warm, it stays in the air longer and takes only short resting breaks.
Territorial defense
Male black swallowtails work hard to claim good hilltop territories to meet visiting females. These chosen perches do not have lots of sweet flower nectar or host plants.
Instead, a territory provides an open lookout spot with an amazing panoramic view. Once a male secures a spot, he defends it from all other male intruders. A territory owner fiercely chases away any rival male that dares fly too close. After a swirling aerial dogfight, the winning male returns straight to his favorite perch.
Early-hatching males from the first summer brood grab the finest hilltop spots first. Males pick prominent landmarks like hilltops, tall bushes, and ridge lines across open country. These high ridges help passing females spot the displaying males from great distances away.
Aggression
Male swallowtails show tremendous energy and aerial aggression when guarding their open territories. Nearly 80 percent of all successful courtship flights happen directly inside these defended zones.
Competition is fierce because there are four males for every single female butterfly. This unequal sex ratio forces males to fight constantly to hold the best perches. A male will dart upward and grapple in mid-air against trespassing rival butterflies.
Mating Systems and How Swallowtails Choose Partners
Swallowtails have evolved clever timing and social habits to help them find healthy mates.
Protandry
Black swallowtail butterflies are protandrous, meaning male butterflies emerge days before the females do. This special timing gives males time to claim the best territories on high hilltops.
Securing a hilltop perch early gives a male the best chance to mate. Meanwhile, female caterpillars spend extra days eating host leaves before building their chrysalis cases. Heavy, well-fed females can produce more eggs once they become flying adults. Male body size does not matter as much during fast aerial territory dogfights.
However, emerging super early carries one big natural downside for the eager male butterflies. A male butterfly's mating energy naturally slows down over several long summer weeks. Males that emerge first might feel worn out when female numbers peak later.
Lek mating
Because males gather on high hills, black swallowtails show classic lekking behavior. A lek is a special animal gathering area used strictly for courtship displays.
Scientists use four rules to identify this system:
- The father butterfly provides no care for the eggs or growing caterpillars.
- Males gather together at special display landmarks like sunny hilltops.
- The gathering area contains no special food resources, only the competing males.
- Visiting female butterflies inspect the males and select their favorite mate.
The hilltops with the most male dogfights attract the highest numbers of females. A female knows that a male holding a tough hilltop is strong and healthy.
Similar Swallowtail Species in North America
Several swallowtail butterflies look very similar to the black swallowtail in flight:
- The Old World swallowtail, known as Papilio machaon
- The cliff-dwelling Indra swallowtail, known as Papilio indra
- The northern Short-tailed swallowtail, known as Papilio brevicauda
- The western Anise swallowtail, known as Papilio zelicaon
Images for kids
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A female laying eggs on parsley leaves
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Tiny round eggs glued to parsley
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First-instar caterpillar in northeast Georgia
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Young larvae showing protective spikes
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Late-instar caterpillar ready to pupate
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The orange osmeterium pushed out for defense
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Caterpillars showing different natural body shades
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A green and brown chrysalis
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Underside view beside an empty chrysalis
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Adult swallowtail resting in Texas
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