Imperial moth vs Promethea moth
These two are easy to mix up. Here's how to tell an imperial moth from a Promethea moth, and whether either one bites or stings.
Imperial moth
Eacles imperialis
Promethea moth
Callosamia promethea
≠The key differences
Imperial moths are more yellow and have different bold patterning; Promethea is typically reddish or dark brown without large yellow patches.
⚖︎Side by side
| Imperial moth | Promethea moth | |
|---|---|---|
| To humans | Non-toxic | Non-toxic |
| Size | Wingspan 80-175 mm (3-7 inches), typically 90-150 mm in many populations | 7.5-9.5 cm wingspan |
| Colours | Yellow, Orange, Rusty brown, Purple-brown markings | Reddish brown, Dark brown, Cream/white, Black |
| Family | Saturniidae | Saturniidae |
| Habitat | Deciduous and mixed woodlands, forest edges, suburban yards with host trees | Deciduous forests, forest edges, riparian corridors and suburban areas with host trees |
| Range | Eastern and central North America from Canada (southern Ontario, Quebec) south through the eastern United States to Mexico; exact range and form vary regionally | Eastern North America: from southern Canada through the eastern United States |
| Active | Mostly spring to early autumn depending on location; adults are nocturnal and fly at night | Late spring to midsummer; one generation in the north, one or two generations farther south; adults fly at dusk and night, males often active during the day |
| Pest? | No | No |
🔍How to spot an imperial moth
- Large wingspan (typically 90-150 mm) with rounded fore- and hindwings.
- Ground colour yellow to orange with distinct purple-brown blotches and wavy crosslines.
- Small dark discal spot on each wing and males with feathery antennae.
- Caterpillars large, green or brown/orange, with long whitish hairs and short horns behind the head.
🔍How to spot a Promethea moth
- Sexual dimorphism: females are reddish-pink with broad pale bands; males are darker brown and smaller.
- Wingspan 7.5-9.5 cm with rounded hindwings typical of silk moths.
- Small translucent or pale cell spot on each forewing.
- Found on or near host trees (spicebush, sassafras, wild cherry, tulip tree, sweetgum).
?Frequently asked questions
What is the difference between an imperial moth and a Promethea moth?
Imperial moths are more yellow and have different bold patterning; Promethea is typically reddish or dark brown without large yellow patches.
Is an imperial moth or a Promethea moth more dangerous?
Imperial moth: Non-toxic. Promethea moth: Non-toxic. Imperial moths and their caterpillars are not venomous. Adults do not bite or sting and are harmless.
Identification from photos is never certain: don't handle insects you can't identify, and get medical advice for bites, stings or allergic reactions.