The butterfly was first discovered in late September when it was still mid-metamorphosis, a mere caterpillar hanging upside down, by Maraleen Manos-Jones in her garden in Albany, N.Y., the Albany Times Union reported.
Manos-Jones, a self-styled butterfly expert, said she first expected the butterfly to emerge damaged, as they often do when slow to develop.
"Instead she came out fabulously," said Manos-Jones. "She's big, she's hearty, she's healthy."
Monarch butterflies are known for making a migration from the Northeast, Pacific Northwest and Canada to Mexico every fall and spring.
Manos-Jones said she knew the butterfly would die if it tried to make its migration south on its own it would die, so she started making phone calls, looking for a way transport the butterfly south to complete its migration.
Southwest Airlines, her first call, agreed to fly both Manos-Jones and the butterfly to San Antonio.
"Southwest's conservation efforts run deep, and after thoughtful consideration, we decided to assist the healthy butterfly down to San Antonio, knowing that it wouldn't make the migration otherwise," said Brooks Thomas, a Southwest spokesman, citing the airlines' concerns for climate change.
"Even one butterfly makes a difference," he said.
The butterfly and Manos-Jones will head to San Antonio on Monday.