Are there invasive reptiles other than Burmese pythons in the United States that people should be concerned about?

Free-ranging reptiles representing dozens of species from around the world are detected in the United States in any given year, usually as a result of escape or illegal release. Fortunately, many of these individuals fail to establish reproductive populations, but  all non-native species can potentially pose risks when introduced.  

Florida is a major transportation hub and has a climate that’s suitable for many invasive species. As a result, the state has the world’s largest number of established, non-indigenous reptile and amphibian species (3 frogs, 4 turtles, 1 crocodilian, 43 lizards, and 5 snakes). Of the vast number of lizard species, one group of specific concern are tegu lizards because of the threat posed to native fauna. Two species of tegus are now established in Florida - Salvator merianae (Argentine black and white tegu) and Tupinambis teguixin (gold tegu) – and a third has been recorded here— S. rufescens (red tegu). Georgia is the only other state with a confirmed population of Black and white tegus lizards. Tegus have been removed from several counties in Florida and Georgia, and most recently in South Carolina and Alabama, but large portions of the U.S. contain suitable habitat and conditions for tegu lizards. 

Green iguanas (Iguana iguana) are another invasive lizard of concern with populations established in Hawaii, Texas, Puerto Rico, and the U.S. Virgin Islands. Green iguanas are known to eat a variety of native plants including plants that are important for endangered species.

Any animal can be problematic when released in places where it is not native. The safest policy is to find an appropriate home for any animal that is no longer wanted because disposal or release in the wild can do great environmental harm.

Learn more:


Related Content

Filter Total Items: 5

Can invasive pythons be eradicated?

The odds of eradicating an introduced population of reptiles once it has spread across a large area are very low, pointing to the importance of prevention, early detection and rapid response. And with the Burmese python now distributed across more than a thousand square miles of southern Florida, including all of Everglades National Park and areas...

What is the brown treesnake?

The brown treesnake is native to parts of Indonesia, the Solomon Islands, New Guinea, and Australia. The snake was first sighted on the island of Guam in the 1950s, probably after stowing away on cargo ships coming from New Guinea. In 2020, a population of brown treesnakes was discovered on Cocos Island, a small atoll of the southern shore of Guam...

How is the USGS helping to prevent the spread of the brown treesnake?

Preventing the spread of the invasive brown treesnake is paramount. It is much cheaper than intervention once a snake population is established. Without rigorous prevention, control (let alone removal) of an introduced reptile species is extremely difficult. In the case of the brown treesnake, prevention efforts include working to detect stowaway...

What is an invasive species and why are they a problem?

An invasive species is an introduced, nonnative organism (disease, parasite, plant, or animal) that begins to spread or expand its range from the site of its original introduction and that has the potential to cause harm to the environment, the economy, or to human health. A few well-known examples include the unintentional introduction of the...

Are invasive snakes dangerous?

Free-ranging snakes representing dozens of species from around the world are discovered in the United States in any given year, usually as a result of escapees or releases from the pet trade, but most of these don't appear to have established a reproductive population. Any animal can be problematic when released in places where it is not native...
Filter Total Items: 6
Date published: August 21, 2018

Genetic Analysis of Florida's Invasive Pythons Reveals A Tangled Family Tree

A new genetic analysis of invasive pythons captured across South Florida finds the big constrictors are closely related to one another. In fact, most of them are genetically related as first or second cousins, according to a study by wildlife genetics experts at the U.S. Geological Survey.

Date published: November 1, 2016

Grappling with Pythons in Florida

In 2003, wildlife scientists carrying out regular nighttime road surveys in Everglades National Park started to see fewer medium-sized mammals. Over the next few years, rabbits disappeared completely, and populations of foxes, raccoons, possums, bobcats, and white-tailed deer were either small or absent.

Date published: November 29, 2012

Invasive Boa Constrictor Thriving on Puerto Rico

MAYAGÜEZ, Puerto Rico— Non-native boa constrictors, which can exceed 10 feet and 75 pounds, have established a breeding population in Puerto Rico, one that appears to be spreading, according to research published in the journal Biological Invasions.

Date published: February 9, 2011

Challenges identified in using models to predict snake and other animal invasions

New research published today has identified challenges in using computer models to predict the potential of pythons or other invasive vertebrate species to spread across portions of the United States, according to the U.S. Geological Survey.

Date published: October 13, 2009

Report Documents the Risks of Giant Invasive Snakes in the U.S.

Five giant non-native snake species would pose high risks to the health of ecosystems in the United States should they become established here, according to a U.S. Geological Survey (USGS) report released today.
The USGS report details the risks of nine non-native boa, anaconda and python species that are invasive or potentially invasive in the United States.

Date published: November 7, 1997

Snake Barrier On Rota is Important Step Toward Preventing Future Spread of Brown Tree Snake

A new way to prevent brown tree snakes from invading was unveiled yesterday by scientists working for the U.S. Department of the Interior’s U.S. Geological Survey and Ohio State University.

Filter Total Items: 14
Invasive Burmese Python
February 1, 2017

Invasive Burmese Python

Invasive Burmese python in the Greater Everglades Photograph credit: Brian Smith, USGS

Alejandro Grajal-Puche shows an Argentine black-and-white tegu
December 31, 2016

Alejandro Grajal-Puche shows an Argentine black-and-white tegu

Alejandro Grajal-Puche shows an Argentine black-and-white tegu (Tupinambis merianae) with a radio-transmitter backpack over its pelvis. USGS photo.

Invasive black and white tegu lizards (Salvator merianae).
October 26, 2016

Invasive black and white tegu lizards (Salvator merianae).

Invasive black and white tegu lizards (Salvator merianae). USGS is working on development of tools for the detection and capture of invasive reptiles in Florida.

October 21, 2015

What's the Big Idea?— Turning to eDNA to Detect Invasive Species

Adam Sepulveda, research zoologist at the USGS Northern Rocky Mountain Science Center, explains a scientists at NOROCK are using environmental DNA — the identification of species through biological information they leave behind in their habitat — to detect invasive species and how this method could change the way scientists find evidence of biodiversity in ecosystems.

video thumbnail: Under Siege: Battling Flying Carp and Giant Pythons and How Science Can Help
July 3, 2012

Under Siege: Battling Flying Carp and Giant Pythons and How Science Can Help

Over the last several decades, non-native species have continued to invade sensitive ecosystems in the United States. Two high-profile species, Asian carp in the Midwest and Burmese pythons in the Everglades, are the focus of much attention by decision makers, the public and the media. Sharon Gross, Robert Reed and Cynthia Kolar discuss issues related to invasive species

Attribution: Ecosystems
Image: Radiotelemetered Tegu
May 24, 2012

Radiotelemetered Tegu

As part of a USGS radiotelemetry study, this tegu carried a transmitter backpack for a year to provide information on how tegus are moving through Florida landscapes

video thumbnail: Record-Breaking Burmese Python (17 feet, 7 inches, 87 eggs) Captured by The USGS, B-roll
March 31, 2012

Record-Breaking Burmese Python (17 feet, 7 inches, 87 eggs) Captured by The USGS, B-roll

Big Ol‘ Gal

This female Burmese python broke the records for her length — 17 feet, 7 inches — and the number of eggs she contained: 87. She was first captured in Everglades National Park by USGS researchers in the spring of 2012, when they followed a "Judas snake" – a male python with a transmitter – and found her nearby in the bushes. USGS scientists then

Attribution: Ecosystems
November 16, 2009

Science Seeks to Stem Snake Surge

Right now in Florida, non-native, giant constrictor snakes—pythons, anacondas, and the boa constrictor—are being found in the wild, and two species have established several breeding populations. The snakes pose a considerable resource management challenge for agencies charged with preserving native ecosystems and species. USGS research wildlife biologist Bob Reed discusses