Fort Indiantown Gap houses the world’s only eastern regal fritillary butterflies

• Katie Knol
  BioRecent Stories

  

  Katie Knol is WITF's General Assignment Reporter & Host.
  
  She graduated from Penn State University in 2024, earning bachelor's degrees in journalism and political science. She has also worked at WPSU, the News Lab at Penn State, The Daily Collegian and CommRadio.

In the rolling grasslands of Lebanon County’s Fort Indiantown Gap, visitors can step away from the military training grounds and into the world’s only remaining population of the eastern regal fritillary butterfly.

With bright orange wings dotted with black and white, the butterflies are fairly easy to spot. During guided tours led by the Pennsylvania Department of Military and Veterans Affairs wildlife staff, visitors scramble to capture a photo before the bright insect flutters away.

“This is not a little butterfly. It is a large, charismatic megafauna,” Virginia Tilden, a wildlife biologist stationed at Fort Indiantown Gap’s wildlife office, said. “Even though it’s a small species compared to other wildlife, butterflies have the ability to capture the heart of the public in a way that other wildlife species don’t necessarily.”

Tilden said the training base’s protected grassland makes it the perfect environment for the picky insect. After hatching, the caterpillar eats only its eggshell, and then survives through winter in a grass clump. When it emerges in the spring, it needs to find violets – the only plant its caterpillars eat.

Because they can survive from June until October — longer than most butterflies — it can be difficult for them to find native plants that bloom for the entire time.

The summer tours give people an opportunity to see the rare butterflies as the eastern regal fritillary moves through the process of being listed as endangered.

Tilden said the eastern subspecies wouldn’t survive without the military’s local presence, which had people with the foresight to treat the species as endangered even though it hadn’t been classified that way.

“Props to them for realizing that and treating them as such because I’ve heard it said, ‘The only failure is extinction,’ and thankfully, we’re nowhere near that,” she said.

They aren’t near extinction, but the eastern regal fritillary butterfly is still extremely rare and hard to spread outside areas without hundreds of grassland acres.

Erika McKinney, another wildlife biologist at Fort Indiantown Gap who leads some of the butterfly tours, said visitors often ask how they can attract the butterflies to their own gardens.

The answer, she said, is usually disappointing.

“These guys do disperse, but they don’t migrate like a typical monarch does,” McKinney said. “They can disperse like several miles, whereas the monarch comes from Canada and can fly all the way down to Mexico.”

These tours are free but require registration and permitting. They take place in June and July.