Bug FAQThoas Swallowtail
Heraclides thoas · Order: Lepidoptera · Family: Papilionidae
Also called: King Swallowtail
Source: Wikipedia
Adult Thoas swallowtails have a wingspan of about 12-14 cm and are common in open country, gardens and plantations. They are yellow-bodied butterflies with narrow brown forewings marked by yellow bands and arcuate spots, and brown hindwings with a long tail and yellow markings. They occur from Texas and the West Indies down to Buenos Aires, but are absent from the Lesser Antilles.
Source: Wikipedia
How to recognize it
The forewings are narrow and mostly brown with a yellow band that narrows toward the rear, plus a row of yellow arcuate spots along the underside edge. Yellow areas are brighter on the undersides, and blue-white arcuate spots sit next to the yellow ones on the upper side. The body is yellow.
Source: Wikipedia
Size
Wingspan ranges from 12 to 14 cm (about 4.7 to 5.5 in).
Source: Wikipedia
Where it lives
It is common everywhere, flying in open country, gardens and plantations.
Source: Wikipedia
What it eats
Caterpillars eat leaves of citrus plants and have also been reported on Piper species.
Source: Wikipedia
Life cycle
The larva lives on plants in the Piperaceae family and on citrus.
Source: Wikipedia
When you see it
Adults are on the wing year-round in tropical areas.
Source: Wikipedia
Where it comes from
Found from Texas and the West Indian Islands south to Buenos Aires, but not on the Lesser Antilles.
Source: Wikipedia
Lookalikes
It can be confused with the giant swallowtail, which looks similar in both larval and adult stages.
Source: Wikipedia
Where it is found in the US
Recorded in 4 of 51 states and DC. Most records: Texas, Georgia, Florida, Kansas.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: native in North America. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
Are they a problem for my garden?
The caterpillars feed on citrus and Piper leaves, so they can damage those plants in a garden or orchard.
Source: Wikipedia
When can I see them?
Adults are active all year in tropical regions and are common in open areas and gardens.
Source: Wikipedia
Same family (Papilionidae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Papilio_thoas
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-22 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-22.