According to the Florida Exotic Pest Plant Council, "invasive exotic pest plants are biological pollutants that wipe out more natural habitat every year than development."

Annually, the State of Florida spends more than $100 million on exotic plant and animal and insect control.

More than 1.7 million acres of Florida's remaining natural areas have been invaded by exotic plant species.

Florida is home to a number of endemic species and unique habitats. Exotic species alter these areas and render habitats unsuitable for or out-compete native species. This reduces biodiversity and puts additional strain on endangered species, of which Florida has more than any other state in the continental U.S.

The species listed below are just a sample of the exotic species that are affecting Florida's flora and fauna.

Exotic plants

Brazilian Pepper

Brazilian Pepper

Origin: South America
Impact: Brazilian pepper was originally brought to the United States as an ornamental plant for people's yards.

It is a fast growing, large plant that has no predators in this country. As a result, it easily and quickly moves to nearby natural areas and displaces native species.
It reduces the diversity of the ecosystem and excludes plants important to the survival of other inhabitants of that ecosystem.

Of all exotic plants in Florida, Brazilian pepper is the most aggressive and widespread, covering more than 700,000 acres in south Florida.

Photo courtesy of South Florida Water Management District

Melaleuca

Melaleuca

Impacts: Melaleuca is an aggressive tree, originally introduced in Florida in 1900 for landscaping and "swamp drying."

It spreads quickly, produces lots of seeds, and grows in very dense aggregations. It out-competes native vegetation, shades out previously open grassland and marsh areas, and destroys suitable habitat, such as sawgrass marshes and wet prairies, for native animals and insects.

Unfortunately, melaleuca has taken over hundreds of thousands of acres in the Everglades. Eradication is extremely difficult because a single tree can produce up to one million seeds per year and can store about 20 million seeds. Seed dispersal is triggered by events such as storms and fires.

The State of Florida spends $3-6 million each year controlling this plant.

Photo courtesy of South Florida Water Management District

Australian Pine

Australian Pine

Impacts: The Australian pine is a fast-growing invasive plant that is well adapted to rapidly colonizing large pieces of land.

As soon as the tree establishes itself, its fallen leaves release chemicals that sterilize the soil, making it impossible for most other plants to grow there.

Also, the Australian pine is a tall tree that produces more shade than other Florida trees. This blocks sunlight from reaching the ground, creating a shady understory in which native plants must struggle to survive.

Native animals and insects suffer from the Australian pine's invasion. The pines displace the native species' food and they do not produce anything that the native species can eat.

This exotic species uses much more water than native species and can deplete an area's water resources. Endangered sea turtles and crocodiles are affected because the pine destroys their nesting habitat.

Florida's beaches are frequently hit by high windstorms. Since Australian pines have shallow roots, they blow over very easily, creating a hazard for people and animals.

Photo courtesy of Collier County Department of Environmental Services

Japanese Climbing Fern

Japanese Climbing Fern

Origin: Eastern Asia

Impacts: Japanese Climbing Fern grows quickly and densely over native shrubs and trees, shading and killing them.


It tends to spread along highways, into open forests, and along stream margins. It can increase in cover to form mats that completely cover native vegetation. Its spores are rapidly dispersed by wind.

As with most exotics, removal must be accomplished by hand, which is expensive and time consuming.

Photo courtesy of South Florida Water Management District

Water Hyacinth

Water Hyacinth

Origin: South America

Impacts: Water hyacinth is a floating plant that can grow up to three feet tall. It grows extremely fast, doubling its population every 12 days. It forms thick mats over waterways, blocking boaters and preventing swimming and fishing.

The mats of plants also block sunlight from entering the water, shading submerged plants. The thick mats also crowd out other aquatic plants. Water hyacinth uses up most of the available oxygen in water, killing fish.

The United States isn't the only country struggling with this plant; it is a global problem currently affecting approximately 56 countries.

Currently, Florida has water hyacinth under control. It is, and will continue to be, a constant struggle, as this plant could easily take over waterways again.

Florida, Louisiana and Texas spend approximately $11 million every year controlling this plant.

Photo courtesy of South Florida Water Management District

Hydrilla

Hydrilla

Origin: Sri Lanka, India and Korea

Impacts: Hydrilla is described as the most serious aquatic weed problem in the state of Florida.

It can grow up to one inch per day. It is resistant to many control techniques, making it extremely difficult to manage.

It is an aggressive and competitive plant that displaces beneficial native vegetation that provides food for prey species, thereby reducing weights and sizes of sportfish.

The state of Florida spends approximately $14.5 million each year on hydrilla control.

Photo courtesy of Tampa Bay Estuary Program

Citrus Canker

Citrus Canker

Origin: Southeastern Asia

Impact: Citrus Canker is one of the most destructive agricultural diseases. It is caused by the bacterium Xanthomonas axonopodis. Over the years it has spread to Japan, South Africa, Australia, Pacific Islands, and North and South America.

Citrus canker was first found in the U.S. in 1910, but was subsequently declared eradicated after millions of citrus and nursery trees were burned. When an area is suspected of being infested with citrus canker, fruit or leaf samples are sent for testing by state and federal laboratories.

It is highly contagious among trees and produces scab-like lesions on fruit, stems, and leaves. An infection may cause defoliation, dieback, severely blemished fruit, reduced fruit quality, and premature fruit drop.

Today, the disease still exists in Florida and continues to threaten valuable citrus crops. It can be spread over short distances by high winds, rain, flooding, insects, birds, and human movement within groves.

Photo courtesy of the U.S. Department of Agriculture

Exotic animals

Monk Parakeet

Monk Parakeet

Origin: South America

Impacts: The monk, or Quaker, parakeet is a temperate to subtropical invasive species that was introduced to the United States in the 1960s.

Monk parakeets build large communal nests in trees, electrical equipment, telecommunication towers and, in some areas of the world, on cliffs. They are considered agricultural pests in their native environment.

Due to the great numbers of nests and their prolific nesting habits, monk parakeets are affecting many electric utilities' ability to provide reliable electric service to customers.

The monk parakeet population doubles approximately every 4.8 years and is expected to grow 14 times larger over the next 10 years if it is not managed appropriately.

European Starling

European Starling

Origin: Europe

Impacts: In 1890, European immigrants released 100 starlings in New York City. A century later, their population has increased to approximately 200 million and they are now found all over the United States and Canada.

The starling is one of the most widespread and abundant birds in North America.

Starlings cause ecological disruption by aggressively driving native birds, such as woodpeckers, great crested flycatchers, tree swallows, eastern bluebirds, and purple martins, from their nests, often destroying eggs and killing nestlings.

For part of the year, starlings travel in large flocks that inhabit trees, buildings, and power substations. The massive amounts of fecal matter produced by the birds have negative health effects and can cause electrical lines to short out.

The large flocks are have caused at least one plane crash and cost the U.S. agricultural industry approximately $800 million per year by damaging crops.

Photo courtesy of Pierce National Wildlife Refuge

Wild Hog

Wild Hog

Origin: Europe

Impacts: Wild hogs, or wild boars, were introduced 400 years ago by Europeans for hunting. Today the species has spread to 23 states and has a total population that numbers more than two million. Florida has the second largest population with approximately 500,000 wild hogs roaming the state.

This species is extremely damaging to the agricultural industry costing the industry over $800 million per year. Wild boars damage crops and transmit diseases to livestock. Diseases can also be transmitted to humans.

Wild boars destroy natural ecosystems by digging up the ground while searching for food in a process called rooting. This behavior destroys ground vegetation, reduces habitat for nesting birds and other animals, causes soil erosion, and can occur on very large patches of land.

Photo courtesy of Texas A & M, Wildlife and Fisheries Sciences

Cuban Tree Frog

Cuban Tree Frog

Origin: Cuba

Impact: Cuban tree frogs are the largest tree frogs in North America.

Cuban tree frogs eat insects, lizards, snakes, mice, hatchling birds, other frogs, and even other Cuban tree frogs. They are nocturnal and spend most of their time in trees. Cuban tree frogs also secrete a poison that can harmful to humans and animals.

They live in urban and natural areas in many south Florida counties, including ecologically valuable areas, such as Florida's wildlife refuges and Everglades National Park.

Cuban tree frogs are quite destructive in their habitats since they have few known predators, out-compete native tree frog species, which causes native tree frog populations to decline, and eat native frogs.

Photo courtesy Creatures Great and Small

Fire Ant

Fire Ants

Origin: Brazil

Impacts: Fire ants are very aggressive, eat voraciously, reproduce extremely quickly, and have a very painful sting.

They eat seeds and move them out of their native habitat, which can alter the landscape and destroy agricultural crops.

They attack, kill, and eat the eggs and nestlings of several species of birds, lizards, and turtles. Severely infested areas can make it impossible to sit on the ground or even stand still too long. In some areas, they have caused the extinction of 40 percent of native insect species.

Fire ants cost the southern US more than $1 billion per year in damage to livestock, public health and fire ant control. It is estimated that fire ants cost homeowners $7.9 million per year on medical treatments for stings, and $11.2 million in structural damages.

Photo courtesy of the U.S. Department of Agriculture

Asian Swamp Eel

Asian Swamp Eel

Origin: Eastern and Southern Asia

Impacts: Asian swamp eels were first introduced to the US in Hawaii in the early 1900s. This species adapts quickly to new environments. It has the potential to become widespread in the U.S. and impact a variety of native aquatic and wetland species, and eventually entire ecosystems.

The Asian swamp eel preys on a variety of animals, including crayfish, shrimp, worms, frogs, tadpoles, and other fishes.

Asian swamp eels can survive both in hot and cold climates, have no known predators in the U.S., can breathe air, and can easily move across land. This had resulted in the population increasing rapidly.

Asian swamp eels have not yet been found in Everglades National Park, but they have been found within less than 0.5 mile from the eastern border of the park.

Photo courtesy of U.S. Geological Survey

Great Toad

Great Toad

Origin: South America, Central America, and Mexico

Impacts: The great toad, or cane toad, is considered the most introduced amphibian in the world.

Bufo marinus is able to reproduce nearly year round. It was originally introduced in an attempt to control insects such as the greybacked cane beetle, Lepidoderma albohirtum, which threatened sugar cane production. However, there is no evidence that it has controlled any pest in Florida or Australia, where it was also introduced to control insects. It is now considered a pest species itself in Australia and the Pacific and Caribbean Islands.

The current population in Florida, thought to inhabit 6-10 counties, threatens native species. The great toad preys on small invertebrates and will even scavenge in urban areas.

It out-competes native amphibians for food and breeding habitat and also causes predator declines, since these predators have no natural immunity to the bufotoxin it secretes. Cats, dogs, native mammals, snakes, and birds are all at risk. Humans may suffer skin rashes or eye irritation when contact is made with the toad's skin.

The extensive canal system in Florida plays a major role in the spread of this invasive species.

Photo courtesy of U.S. Geological Survey

Blue Tilapia

Blue Tilapia

Origin: Africa and Middle East

Impacts: The blue tilapia, which has established itself in almost all of central and south Florida, represents a significant threat to native ecosystems.

This fish competes with native fauna for spawning grounds, food, and extended habitat. Its impacts can be clearly seen in areas with dense tilapia populations, which are nearly devoid of vegetation and native fish.

The occurrence of blue tilapia drastically alters natural fish communities. This species is a great threat to the integrity of the Everglades National Park and other natural areas, where it is considered a major management problem for the National Park Service.

Photo courtesy of Florida Fish and Wildlife Conservation Commission

Spectacled Caiman

Spectacled Caiman

Origin: Central and South America

Impacts: The spectacled Caiman may be easily confused with the American alligator or crocodile, although it is an exotic, non-native species. The caiman has slight morphological differences, such as color and shape of the snout, when compared to its reptilian cousins. Adults may attain a length of 6-8 feet.

Caimans inhabit freshwater marshes, heavily vegetated ponds, lakes, and canals. They are established in Southeastern Dade County, Florida, and have been reported in other areas, such as Everglades National Park.

These reptiles compete for food and habitat with the American alligator and are more aggressive.

Their introduction to Florida ecosystems is most likely the result of discarded pets.

Photo © F. Wayne King