Federal officials have found unwanted visitors — invasive little fire ants — on Kilauea at Hawai‘i Volcanoes National Park.

The ants, which deliver a painful sting when disturbed, were found in the popular Steam Vents area and Mauna Ulu parking lot at the national park, and are the first known populations in the park. The discovery comes not long after Kilauea reopened in late September following 134 days of closure due to eruptions and seismic activity.

National Park Service officials said intensive sampling is underway to determine whether the ants are more widespread. Park scientists are also working with partners to address the threat quickly, and evaluating control options while ensuring visitor safety and protecting native ecosystems.

So far, no bites have been reported, and no ant-related closures are in effect.

“We are concerned for the health and safety of our staff and visitors, and the fragile Hawaiian ecosystems of the park,” said park ecologist David Benitez in a news release. “Little fire ants really depend on humans to move them around. We need everyone to ensure their vehicles and gear are free of ants before coming into the park.”

Little fire ants (Wasmannia auropunctata), which were first discovered on the Big Island in 1999, can have devastating impacts on native ecosystems and human health. They are red-orange and measure only about 1.5 millimeters in length, or as long as a penny thick. They infest agricultural fields and farms, damaging crops, and in communities they can sting pet dogs and cats in the eyes, resulting in blindness.

Since 2014, Hawai‘i Volcanoes has sought to prevent the introduction of little fire ants by monitoring equipment, construction material and the vehicles that transport them before they enter the park. Officials have intercepted the small, biting ants a dozen times this year.

More information on little fire ants and how to prevent spreading them is available at littlefireants.com. If you find little fire ants, call 643-PEST or visit 643pest.org.