Rod Williams / Red or Small postman (Heliconius erato) feeding on milkweed, Central and South America.

Angelo Gandolfi / Red postman butterfly (Heliconius erato) (above) and Tiger longwing (Heliconius hecale) La Paz Waterfall Gardens, Costa Rica.

Nick Hawkins / Small postman butterfly (Heliconius erato) photographed on white background, Costa Rica.

Loic Poidevin / Red postman butterfly (Heliconus erato) on leaf, captive, occurs in the Americas.

Loic Poidevin / Postman butterfly (Heliconius melpomene) captive, occurs in the Americas.

Adrian Davies / Postman butterfly (Heliconius melpomene), Butterfly farm, Captive. Occurs in Central and South America.

Loic Poidevin / Two Postman butterflies (Heliconius melpomene) mating, captive, native to Brazil.

Ernie Janes / Jack russell terrier with letters and postman's sack

Stephen Dalton / Postman buttefly (Heliconius melpomene) at rest on leaf

PREMAPHOTOS / Red or small postman butterfly (Heliconius erato) males at their communal roost at night in Amazonian rainforest, Brazil

Rod Williams / Postman butterfly {Heliconius melpomene} feeding on hibiscus, captive, from South America

Thomas Marent / Postman Butterfly (Heliconius melpomene) butterfly in captive breeding program, Colombia

Tom Vezo / Postman Butterfly (Heliconius melpomene) feeding on flower nectar, Tucson Botanical Gardens, Tucson, Arizona

Joel Sartore / Photo Ark / Red postman butterfly (Heliconius erato) portrait, Urku Center, Peru. Captive.

Joel Sartore / Photo Ark / Red postman butterfly (Heliconius erato) resting, portrait, Urku Center, Peru. Captive.

Edwin Giesbers / Common postman butterfly (Heliconius melpomene) resting on leaf upside down. Captive.

Edwin Giesbers / Common postman butterfly (Heliconius melpomene) resting on leaf, wings open. Captive.

Edwin Giesbers / Digital composite of Tiger longwing butterfly (Heliconius hecale), Red postman butterfly (Heliconius erato) and Banded Orange Heliconian butterfly (Dryadula phaetusa) on flower. Captive.

Edwin Giesbers / Courtship of two Postman butterfly (Heliconius melpomene) on flower. Captive.

Dave Watts / Running postman (Kennedia prostrata). Tasmania, Australia. October.