V Argentine Invasion: the lizard that proliferates in the United States

As in the mythical television series of the 80s, "V Extraterrestrial Invasion", where some aliens who turned out to be lizards invaded our planet, some lizards originating in Argentina are invading the United States.

The Argentine tegu, better known as the overo lizard, is a species of lizard native to Argentina, although its geographical area extends from the centre and south of Brazil to the south of the Amazon River, the east of Bolivia, the centre and east of Paraguay, the entire territory of Uruguay, and the northeast and centre of Argentina.

It is a large lizard that can reach a metre and a half in length, weighing almost 6 kilos and is omnivorous. It mainly feeds birds, reptiles and turtles, insects, vegetables, fruits and eggs... anything that can fit in their jaws.

They are extremely voracious, and that motivates the concern of the Florida Wildlife and Fisheries Commission (FWC), since they have proliferated widely in southern Florida. It has also appeared throughout the southeast of the United States. USA, which poses a potential threat to native species and farmers.

Invasive species

Tegu are extremely resistant, so their spread is difficult to control or reduce once the species has established itself.

These lizards are very coveted by fans of exotic animals, since they are docile, somewhat affectionate and like to sunbathe, many people adopt them as pets. Although most of these lizards have been raised in the U.S. In the United States, between 2000 and 2010, about 80,000 live tegus were imported from South America, since in many states it is legal to have them as pets.

It is estimated that only a small minority of Tegu in captivity have escaped or been released, and biologists suspect that they may be reproducing, which evidently worsens the situation. So it is so that the state of South Carolina enacted a ban against the possession of reptiles's pets in 2021, while Georgia passed a law in 2022 to regulate the possession of tegu (a license and microchip are required of all captive tegu).

In the state of Florida, the state Wildlife Conservation and Fisheries Commission has banned the commercial breeding, sale, ownership and reproduction of non-native tegu lizards in Florida, as well as iguanas and other non-native animals, as of June 2024. And the owners of these pets have been summoned to comply with the regulations that require cement enclosures for reptiles that live outdoors.

Concern about damage to the habitat

The main concern of wildlife officials is that invasive species compete with native animals for food and other resources, cause damage to the habitat and transmit diseases.

Different wildlife departments have led different strategies to combat tegu. It is that since lizards have few predators, they can multiply quickly. Although tegu do not pose a threat to humans, they can sometimes be grumpy and difficult to handle, and they have rarely bitten people.

In Georgia, the Department of Natural Resources together with the U.S. Geological Survey. UU. (USGS) and the University of Southern Georgia, evaluate the population of tegu, documenting their diet and reproductive status, and sacrificing some specimens.

Attempts to control it

Other strategies have been to set traps. In 2020 alone, in southern Florida, the traps placed by the USGS captured more than 900 tegu near the Everglades National Park, and this strategy seems to have been able to control the tegu population.

In Georgia, the USGS set traps with eggs coated with capsaicin (the substance that generates the itching found in chilies), and lizards seem not to be bothered by the spiciness, so the results have not been satisfactory.

Different scientific organisations continue to explore different strategies to combat the invasion of Argentine lizards.

For now, the tegu is winning.