Fort Indiantown Gap, Annville, PA (WHTM) When you say the words “military base” you generally don’t think “wildlife habitat.” But Fort Indiantown Gap, the only live-fire, maneuver military training facility in Pennsylvania, is also home to thousands of species of plants and animals. This includes a butterfly so rare the Gap is the only place it’s found in the Eastern United States. During the months of June and July, you will be able to come and see it.

The butterfly in question is the regal fritillary (Speyeria idalia). According to the U.S. Department of Agriculture, the regal fritillary butterfly was once found throughout much of the United States, but has suffered badly from habitat loss. It’s considered critically imperiled in Pennsylvania, having endured a massive population drop since 1980.

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On June 30, and July 1, 7, and 8, the Pennsylvania Department of Military and Veterans Affairs (DMVA) wildlife staff will provide free guided tours of the regal fritillary butterfly habitat. Attendance is limited, and all visitors, including children, must register online at: 

to obtain a free permit. To attend a tour, you must present a permit for that specific date and time slot. No rain dates will be provided. Attendees will be required to travel from the meeting location to the tour location in their personal vehicles. Tours will last approximately one hour plus driving time. Meeting location and parking information will be provided after obtaining a permit.

Tours will be on foot on gravel roads and mowed paths. Please bring drinking water and wear appropriate clothing and footwear for uneven terrain. (Keep in mind there will be little or no shade on the tour route.) Wandering off the path, into the fields, or away from your tour guide is prohibited.

“These tours allow the public to see this rare butterfly and its grassland habitat on military training ranges, as well as the many other natural wonders on the 17,000-acre military installation,” said John Fronko, director DMVA Bureau of Environmental Management. “Staff will also highlight a variety of animals and plants found at Fort Indiantown Gap and how the military presence on the installation is vital to the persistence of these species and their ecosystems.”

The Gap has a diverse population of plants and animals, many of which are rare and considered species of conservation concern. It is home to 49 species of mammals, 143 species of breeding birds, 37 species of reptiles and amphibians, 35 species of fish, more than 800 species of plants, and many notable species of invertebrates including 86 species of butterflies and more than 500 species of moths. These species persist at FTIG because it provides an assortment of high-quality habitats. This includes rare early successional ecosystems such as grasslands, thickets, shrub lands, and young forests which were created and maintained from disturbances caused by military training, fires, and conservation efforts. The installation is home to 1,000 acres of scrub oak and pitch pine barrens and approximately 2,200 acres of native grassland habitat – the largest in the state.

General inquiries about the tours can be emailed to or call (717) 861-3299.