Eastern Black Swallowtail
Papilio polyxenes
Darwin Core (DwC) Taxonomic Classification
Papilio polyxenes Fabricius, 1775
Quick Rearing Snapshot & Biology Overview
Rearing and biology notes for Eastern Black Swallowtail
Dill (Anethum graveolens), Fennel (Foeniculum vulgare), Parsley (Petroselinum crispum)
~30 Days total (Egg → Butterfly)
Pupal Diapause (Does Not Migrate)
Girdle / Twig Sling
Thermal Degree-Day Hatch SimulatorInteractive
Slide ambient temperature to see how heat accelerates metamorphosis for Eastern Black Swallowtail
*Calculated via standard insect thermal summation models (base threshold 50°F / 10°C).
Raising Eastern Black Swallowtail in the Classroom?
Access our free 4-Week NGSS Metamorphosis Unit, printable daily growth observation logs, student job badges, and certified release certificates.
Eastern Black Swallowtail
Papilio polyxenes (Fabricius, 1775) — Papilionidae • Papilioninae
- Velvety jet-black ground color across all wings
- Double row of bright yellow submarginal triangular spots
- Hindwing with iridescent cobalt-blue dusting between yellow rows (especially prominent in females)
- Classic elongated spatulate tails on hindwing vein M3
- Prominent anal eyespot: orange-red circular ring enclosing a centered black pupil
Larval Host Flora:
Silo 02 BotanyOnly supply fresh, pesticide-free foliage from these verified native botanical species:
- •Dill (Anethum graveolens)
- •Fennel (Foeniculum vulgare)
- •Parsley (Petroselinum crispum)
- •Golden Alexanders (Zizia aurea)
- •Rue (Ruta graveolens)
Key Husbandry Tips
Silo 04 Husbandry- •Caterpillars have an orange defensive scent organ (osmeterium) behind their head that emits an unharmful foul carrot-like odor if startled.
- •Sturdy twigs set at about 45 degrees go into the enclosure, because the larva spins a silk girdle loop to hold itself before forming the chrysalis.
- •Late-fall chrysalises enter diapause (dormancy). Store them in a cold, unheated garage or protected screened porch through winter to emerge in spring.
- •Raising black swallowtails on dill, fennel and parsley runs from the egg through to overwintering the chrysalis.
- •Black swallowtail and monarch caterpillars are compared side by side by markings and food plant.
Do Black Swallowtails Migrate? (The Overwintering Diapause Protocol)
Strategy: Non-Migratory Pupal Diapause (Winter Chrysalis Dormancy)
Unlike Monarchs which fly to Mexico, Eastern Black Swallowtails (Papilio polyxenes) DO NOT migrate south. They survive sub-zero northern winters exclusively through pupal diapause (metabolic dormancy) inside a hardened chrysalis suspended by a silk girdle.
Autumn daylengths dropping below 13.5 hours of sunlight halt brain hormone PTTH (prothoracicotropic hormone), preventing adult organ differentiation.
Synthesizes natural glycerol and sorbitol polyols in hemolymph (insect blood), acting as cellular antifreeze capable of withstanding temperatures down to -20°F (-29°C).
The mesh cage goes in an unheated garage, shed or screened porch, kept cool and sheltered from direct rain and rodents, and misted lightly once a month. A heated house is not used, because it breaks the diapause the pupa is holding.
No! This is one of the most common myths in butterfly biology. Black Swallowtails are non-migratory resident butterflies that survive northern winters as dormant chrysalises attached to twigs, tree bark, and fence posts.
It has entered diapause! Caterpillars that pupate in late August, September, or October sense shortening daylight and stay dormant until the following spring (5 to 7 months).
No! Chrysalis color is determined by the background texture: caterpillars that pupate on woody twigs or mesh become brown, while those on green foliage become green. Both are completely healthy.
That is the osmeterium — a harmless, non-toxic defensive glandular organ that extrudes when startled, emitting an organic carrot/citrus odor to scare away ants and spiders.
No. Artificial indoor heating will break dormancy mid-winter, causing the butterfly to hatch in January when there are no outdoor nectar plants or mates.
Frequently Asked Questions (Eastern Black Swallowtail)
Direct answers to the most common rearing, diet, and metamorphosis questions
Master Research Guides for Eastern Black Swallowtail
Rearing protocols, lifecycle stages, and field husbandry
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