Black swallowtail vs Old World swallowtail
These two are easy to mix up. Here's how to tell a black swallowtail from an old World swallowtail, and whether either one bites or stings.
Black swallowtail
Papilio polyxenes
Old World swallowtail
Papilio machaon
≠The key differences
Black swallowtail has a darker ground colour (more black) and different pattern of blue/red scaling; P. polyxenes often lacks the large yellow field seen in P. machaon.
⚖︎Side by side
| Black swallowtail | Old World swallowtail | |
|---|---|---|
| To humans | Non-toxic | Non-toxic |
| Size | 6.5-10 cm wingspan | 65-86 mm wingspan (regional variation exists) |
| Colours | Black, Yellow, Blue, Orange | Yellow, Black, Blue, Red-Orange |
| Family | Papilionidae | Papilionidae |
| Habitat | Open areas, gardens, meadows, roadsides and fields where host plants (Apiaceae and some Rutaceae) grow | Flower-rich meadows, grasslands, river valleys, coastal marshes, gardens and roadside verges |
| Range | Southern Canada and most of the United States east of the Rocky Mountains, plus the Southwest; south through Mexico and Central America to northern South America | Holarctic: much of Europe, North Africa, temperate Asia (east to Japan), and in North America where closely related subspecies occur |
| Active | Spring through fall (multiple broods in warm areas); diurnal (active during daylight) | Primarily spring and summer (one to three broods depending on latitude); diurnal, most active on warm, sunny days |
| Pest? | Yes | No |
🔍How to spot a black swallowtail
- Black wings with a band of yellow spots across forewing; hindwings have blue scaling and orange submarginal spots
- Distinctive swallowtail 'tails' on the hindwings
- Caterpillars are initially dark and white-banded (bird-dropping mimic), later becoming green with black bands and orange spots
- Wingspan typically 6.5-10 cm
🔍How to spot an old World swallowtail
- Large yellow butterfly with bold black veins and marginal black banding on forewings
- Hindwings bear a tail-like extension and a line of blue spots plus a red-orange eyespot near the rear margin
- Distinctive swallowtail shape — look for the tails on the hindwings
?Frequently asked questions
What is the difference between a black swallowtail and an old World swallowtail?
Black swallowtail has a darker ground colour (more black) and different pattern of blue/red scaling; P. polyxenes often lacks the large yellow field seen in P. machaon.
Is a black swallowtail or an old World swallowtail more dangerous?
Black swallowtail: Non-toxic. Old World swallowtail: Non-toxic. Adults do not bite or sting and are harmless. Harmless to people: adults do not bite or sting.
Identification from photos is never certain: don't handle insects you can't identify, and get medical advice for bites, stings or allergic reactions.