North American Butterflies and Moths List

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U.S. Geological Survey

Butterflies of North America

Thoas Swallowtail (Papilio thoas)
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Thoas Swallowtail (Papilio thoas Swainson)

Wing span: 4 1/8 - 5 inches (10.5 - 12.8 cm).

Identification: Upperside of forewing has diagonal yellow band of square spots in a neat row.

Life history: Caterpillars resemble bird droppings and rest exposed on leaves.

Flight: Year-round in the tropics, April-July in south Texas.

Caterpillar hosts: Plants in the citrus family (Rutaceae) including Citrus spp., prickly ash (Zanthoxylum americanum), hop tree (Ptelea trifoliata); six species in the Piperaceae family.

Adult food: Flower nectar, including lantana, cesalpina, and bougainvilla.

Habitat: Mid-elevation tropical forests and lowland edges.

Range: South Texas south to Brazil. Very rare stray into Kansas and Oklahoma.

Conservation: Not needed in the United States.

Management needs: None in the United States.

The Nature Conservancy Global Rank: G5 - Demonstrably secure globally, though it may be quite rare in parts of its range, especially at the periphery.


Opler, P. A. and V. Malikul. 1992. A field guide to eastern butterflies.
     Peterson field guide #4. Houghton-Mifflin Co., Boston. 396 pages, 48
     color plates.

Scott, J. A. 1986. The butterflies of North America. Stanford University Press,
     Stanford, Calif. 583 pages, 64 color plates.

Author: Jane M. Struttmann

Thoas Swallowtail (Papilio thoas)
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