Since 1997, Florida has released Australian insects to help control melaleuca in the Everglades; its invaded range has shrunk by nearly 75% alongside herbicide and mechanical removal

Most people would not expect a beetle to help restore a wetland. But that is roughly what happened in the Florida Everglades, where the program is often cited as a success in invasive-species management.

In the late 1800s, growers and land developers introduced an Australian tree, melaleuca (Melaleuca quinquenervia), into South Florida, hoping it would help dry out swampland and serve as an ornamental landscape tree. The plan had the opposite effect. Melaleuca spread aggressively through the Everglades, crowding out native sawgrass and hardwood hammocks, altering fire patterns, and drawing water from an ecosystem that depends on precise hydrology. According to an official USDA Forest Service publication documenting the program’s outcomes, melaleuca-dominated land in South Florida once covered close to half a million acres (about 200,000 hectares), an area larger than Rhode Island.

How USDA scientists chose Australian insects


Cutting melaleuca down or spraying it with herbicide had an unintended effect. Disturbed trees often released a flood of seeds, and a single mature tree can hold up to 9 million viable seeds, so mechanical removal alone tended to trigger regrowth rather than stop it. Land managers needed a control method that would keep working without repeated labor or chemicals and would spare Florida’s native plants.

That search led USDA researchers to melaleuca’s native range. Scientists surveyed ecosystems for insects that fed exclusively on the tree, then spent years testing candidates in quarantine to confirm they posed no risk to U.S. crops or native species. The first agent cleared for release, a snout-feeding weevil called Oxyops vitiosa, was introduced into the Everglades in 1997. According to a peer-reviewed USDA Agricultural Research Service report, the weevil established quickly at release sites and began feeding on new melaleuca growth almost immediately.

Two agents followed in later years: a sap-feeding psyllid and a stem-galling midge. Each insect attacks a part of the tree, so together they weaken seed production, damage new foliage, and slow the growth of young seedlings before they can mature into seed-bearing trees.

What the data shows

The key question is whether the data support that conclusion. Data from the USDA Agricultural Research Service and associated biological control studies indicate that coordinated management reduced the melaleuca-dominated area in south Florida from approximately 200,000 hectares (close to half a million acres) to under 50,000 hectares, a reduction of roughly 75 percent. The USDA Agricultural Research Service also reports that melaleuca density and spread have drastically decreased. Integrated control efforts have reduced melaleuca-dominated areas by nearly 75 percent, while ongoing management aims to limit its footprint even further across the region.

While the insects were an important part of the strategy, they worked alongside biological, chemical, and mechanical control methods. The USDA researchers, the South Florida Water Management District, and the U.S. Army Corps of Engineers all worked together for more than two decades to manage and control melaleuca across the region. They used insects, herbicides, and machines to control the trees, with insects helping suppress regrowth after cutting or treatment.

Agencies across Florida spent tens of millions of dollars on the effort, a reminder of how much time and money long-term invasive species control actually requires.

Why this Everglades restoration story matters now

The melaleuca program offers a valuable model for researchers and land managers, particularly for integrated pest management strategies that combine multiple control methods. USDA Agricultural Research Service studies have found that pairing host-specific insects with traditional control methods can meaningfully reduce melaleuca's spread. The melaleuca program can reduce the number of melaleuca plants, limit seed production, and prevent regrowth over many years. The biocontrol insects helped agencies rely less heavily on repeated chemical treatment than they otherwise would have needed, even though herbicides remained part of the overall strategy.

The program also coincided with efforts to restore native plants and one of North America's most important wetlands. The program took years to show results. More than ten years were spent ensuring the insects were safe for the environment, and the results became clear nearly twenty years later.