Invasive Species Most Wanted

These eight plants and animals pose a serious risk to our ecosystem, but there’s hope they could be eliminated.

By Jacob Shafer

The Maui Invasive Species Committee’s job is hard.

The Valley Isle exceeded 3 million visitors for the first time in 2019, according to the Hawai‘i Tourism Authority (HTA). As the pandemic recedes, we should expect to return to that level of visitor arrivals. Shipping containers and cruise ships flow into our harbors daily. Inspectors are perpetually overworked and understaffed, according to the state Department of Agriculture. The threat of invasive species is omnipresent.

“Our mission is preventing, controlling or eliminating the greatest threats to our watersheds, ecological resources, our community, and our way of life,” MISC representative Serena Fukushima told Maui Times. “The best thing we can do is prevention—making sure these plants and animals don’t come here in the first place.”

Inevitably, however, invaders arrive.

“About 75 percent of our landscape is dominated by non-native plants and animals,” Fukushima said. “If you look outside your window right now, chances are it didn’t originate in Hawai‘i.”

What about more entrenched invasive species, including cats, rats, mongooses, kiawe, and…well…humans?

“As an agency, we have methods for choosing our targets,” Fukushima said. “But we need to be realistic. Some species are more troubling than others.”

With that in mind, here are the top eight flora and fauna on MISC’s “most wanted” list. They aren’t necessarily the most harmful species on-island. That said, MISC believes they pose a significant threat—and holds out hope for control or elimination.


Little Fire Ant

These yellow-red pests—referred to by MISC and other groups as LFA—are about as long as a penny is thick. They don’t build traditional ant hills; instead, they nest in trees, potted plants, and other tough-to-identify spaces. Their bite is irritating to humans and potentially blinding to pets, and they have a symbiotic relationship with aphids, white flies, and other parasitic insects.

Native to Central and South America east of the Andes, LFA were first identified on Maui in 2009, in Waihe‘e, and sightings have subsequently been reported islandwide. Based on genetic analysis, they are believed to have originally been brought to Puna on the Big Island in a shipment of nursery plants from Florida in 1999. In concert with the Hawai‘i Department of Agriculture, MISC considers the LFA controlled, but the threat of spread remains.


Blessed Milk Thistle

Purple flowers and shiny green leaves identify this Southern European native, which ranges from 2 to 6 ft. in height. A single Blessed Milk Thistle can produce as many as 6,000 seeds and contains high levels of nitrate, which is poisonous for grazing animals such as cattle and sheep.

For now, according to MISC, it’s isolated mostly to Makawao, where eradication efforts are ongoing.


Coqui Frog

Native to Puerto Rico, coqui frogs are small (slightly more than 1 inch long). They’re also ear-splittingly loud, as anyone who lives in their vicinity will attest. The nighttime mating call of the male coqui can top 90 decibels, about the same as a typical lawn mower running two feet from your ear. And they’ve taken hold on Maui, impacting everything from native ecosystems to tourism and real estate values.

MISC and other agencies are trying to contain Maui’s coqui population with the help of landowners and volunteers by spraying citric acid, which kills them on contact. However, their resources are limited and funding is hard to secure. MISC warns, “Without a significant and sustained increase in efforts, the vision of a coqui-free Maui will become impossible.”

With a stronghold in Maliko Gulch and established populations on the North Shore as well as West, Central and South Mau, coqui are on the verge of a permanent, islandwide invasion.


Ivy Gourd

Colloquially known as “Thai spinach,” ivy gourd features white flowers and red fruit and its native range stretches from Africa to Southeast Asia and Northern Australia. It grows rapidly–up to 4 in. in a single day.

Infestations are centered in Kapalua, Lahaina, and Kihei, and it’s also been found in Makawao and Waiehu, and on Lana‘i. MISC said it is working to monitor and control the plant in these areas.


Fountain Grass

Similar to pampas grass in appearance, fountain grass increases fire risk, according to MISC and other state agencies.

Native to Africa, fountain grass grows in clumps up to 3 ft. in height with pale yellow or purple seed shoots. It’s found in Waiehu and Kahului, with a limited population on Lana‘i. The state Department of Agriculture successfully eliminated fountain grass on Molokai in the ‘90s.



A tree with oval-shaped leaves and purple berries that can grow up to 50 feet tall, Miconia shades out native plants and creates an “umbrella” effect that saps rainwater, while its shallow roots cause erosion. A full-grown Miconia tree produces six to nine million seeds a year, and the seeds remain viable for more than a decade.

Miconia are native to Mexico as well as Central and South America. The trees have spread across nearly 40,000 acres in East Maui. Today the focus is on containment rather then eradication.


Pampas Grass

A clumping plant that grows as tall as 6 ft., Pampas Grass is illegal to propagate, transport, or export in Hawai‘i. Native to South America, it was introduced locally as an ornamental for its white-to-purple feather-like plumes.

Local trouble spots include Upcountry Maui and Haleakala National Park, but Pampas seeds are windborn and easily spread, according to MISC.



Cultivated for its medicinal properties, Mullein grows up to 10 ft. in height and features oval leaves, wooly “hairs,” and yellow flowers.

A drought-tolerant plant common to Europe, North Africa and parts of Asia, it can choke out native vegetation and has been observed near the top of Haleakala (at elevations above 9,000 ft.) as well as parts of Kula.

To report an invasive species sighting, call the state hotline: 808-643-PEST (7378).
For more information on eradication efforts and what you can do, visit

Jacob Shafer