Agriculture officials respond after invasive butterfly makes appearance in Key West

KEY WEST, Fla. – A Key West woman spotted a curious-looking caterpillar in her backyard and it caught the attention of state officials.

Heather Ludwick and her daughter noticed a caterpillar on their Meyer lemon tree.

“When we first saw it, it was this big and it was brown and we thought it was a native species,” Ludwick said.

But then, it turned green, and since they didn’t recognize it, they turned to the Internet to identify it.

“We used the citizen science website to take a picture to try to identify it and then the comments started coming in,” Ludwick said.

Another homeowner on that website contacted the state of Florida, and not long after scientists with the Department of Agriculture were at their door.

“And then the Department of Agriculture showed up at my house and had questions! So it’s been quite an adventure,” Ludwick said.

“We sent a team down and we did collect a lime swallowtail at that location,” said Dr. Trevor Smith with the Florida Department of Agriculture.

Scientists identified the species as an invasive lime swallowtail, a butterfly originally from Asia.

“About 20 years ago it was introduced to the Caribbean and it’s kind of been island hopping ever since,” Smith said.

Scientists think it might have been blown into Key West from Cuba during a frontal boundary or tropical system.

It has not been found anywhere else in the Florida Keys.

The spotted butterfly is a strong flier, known to spread rapidly and lay eggs on citrus trees, which is damaging for young plants.

“The very small caterpillars, kind of look like bird droppings,” Smith said.

“As soon as that hatches the larvae starts feeding on the leaf material,” Smith said.

Not only is it concerning for citrus, but also on the Native Schaus Swallowtail. The Schaus Swallowtail is an endangered species scientists are trying to re-introduce to the Keys.

“There’s no way we’re going to be able to re-introduce the native if this exotic has pretty much occupied the same niche,” Smith said.

Anyone who might spot what they think is an invasive species is always encouraged to call it in.

To help stop the spread of this pest, if you see eggs, caterpillars or pupae on your citrus plants, collect them, place them in a sealed container and contact the Florida Department of Agriculture Helpline at 1-888-397-1517 or

About the Author:

Janine Stanwood joined Local 10 News in February 2004 as an assignment editor. She is now a general assignment reporter. Before moving to South Florida from her Washington home, Janine was the senior legislative correspondent for a United States senator on Capitol Hill.