The Cuban treefrog, Osteopilus septentrionalis (Figure 1), is native to Cuba, the Isle of Youth (an island province of Cuba also known as Isle of Pines), the Cayman Islands, and the Bahamas. It is an introduced species in Florida, and the earliest confirmed records date to the 1920s in the Florida Keys. The first Cuban treefrogs in Florida likely arrived as stowaways in shipping crates originating from the Caribbean. By the mid-1970s, they had dispersed throughout most of southern Florida. As of 2017, there are established breeding populations as far north as Cedar Key on Florida's Gulf Coast, Jacksonville on the Atlantic Coast, and Gainesville in north-central Florida (Figure 2). This species certainly has the potential to expand its range in Florida and the Southeast, and isolated individuals have been documented in coastal South Carolina, Georgia, Alabama, Mississippi, Lousiana, and Texas. The number of reports of Cuban treefrogs from the Florida panhandle continue to increase, and this invasive frog may already have small populations established in this region of the state. Cuban treefrogs spread by hitchhiking on ornamental plants, motorized vehicles, boats, etc. The Cuban treefrog is considered an invasive species in Florida.
The ultimate distribution of Cuban treefrogs in Florida and the southeastern United States will likely be dictated by climate. A scientific paper published by German biologists in 2009 suggested that human-caused climate change may create conditions suitable for Cuban treefrog colonization and breeding and allow this frog to become established across much of the southeastern US. An unusually long period of cold temperatures in January of 2010 appears to have killed many Cuban treefrogs in peninsular Florida, but the population decline was only a temporary setback for this invasive frog. Cuban treefrog populations have rebounded throughout the peninsula and are likely to continue to expand their range into Florida's panhandle and beyond.
Identifying Cuban Treefrogs
The Cuban treefrog is a member of the frog family Hylidae. All of Florida's treefrogs, including Cuban treefrogs, have expanded pads on the ends of their toes that allow them to climb trees, shrubs, windows, and buildings. Their toe pads help distinguish treefrogs from other frogs such as toads and aquatic frogs like bullfrogs. Cuban treefrogs have exceptionally large toepads as compared to Florida's native treefrogs (Figure 3).
Cuban treefrogs are the largest species of treefrog in Florida, and adult females may exceed 6 inches in length. Most Cuban treefrogs, however, range from 1–4 inches long. They have very large eyes, giving them a somewhat "bug-eyed" appearance. They usually have rough or warty skin, sometimes have a pattern of large wavy markings or blotches on their back, and frequently have stripes or bands on the dorsal surface of their legs. The colors of Cuban treefrogs vary a lot. Most often they are creamy white to light brown, although they can be green, gray, beige, yellow, dark brown, or a combination of these colors. They have a yellowish wash where their front and rear legs are attached to their body.
Several of Florida's native treefrogs superficially resemble Cuban treefrogs. These frogs, like Cuban treefrogs, also show considerable variation in colors and markings, but generally are smaller and have smaller eyes. Therefore, it can be difficult to distinguish native treefrogs from invasive Cuban treefrogs. However, there are ways to confidently identify all of Florida's treefrogs, and with a little bit of practice anyone can tell them apart. The three native species most likely to be found with Cuban treefrogs are the squirrel treefrog, barking treefrog, and Cope's gray treefrog. Adult squirrel treefrogs are small, and only grow to 1.5 inches. Their color varies a lot, and they may be bright green, dull green, grayish, or brown. They may or may not have a pattern on their back, but their skin is smooth and lacks warts. Barking treefrogs are much bigger and plump, growing to 2.5 inches long. Their overall color varies from yellowish-green, to dark green, to brown. On rare occasions they have a lot of white or their backs. They almost always have numerous round spots on their back and a white upper lip. Their back skin lacks distinct warts, but appears granular or slightly rough. Cope's gray treefrogs closely resemble Cuban treefrogs; both have a yellow-colored wash in their groin and armpits, and both have warts on their back. They also often have obvious, dark wavy bands on their back and sides. The best way to identify a Cope's gray treefrog is by the light-colored blotch below each eye. For details and images of Florida's treefrogs, and to learn how to differentiate them, please visit the UF/IFAS Wildlife website at http://ufwildlife.ifas.ufl.edu/index.shtml and follow the "Florida Frogs" link in the left hand column. Also visit the websites listed at the end of this document to find additional digital images of Cuban and native treefrogs.
Cuban Treefrog Ecology and "Natural History"
Cuban treefrogs are found in a variety of natural and human-modified habitats in Florida. Natural habitats invaded by Cuban treefrogs include pine forests, hardwood hammocks, and swamps. In urban and suburban settings they are most commonly found on and around homes and buildings, and in gardens and landscape plants. They also occur in agricultural settings, orange groves, and plant nurseries. They occur throughout Florida's peninsula (Figure 2), and are continuing to expand their range to the north. The expansion of their range is augmented by the activities of people. Cuban treefrogs are transported to new areas as stowaways on cars, trucks, and boat trailers as well as in ornamental plants and trees that are shipped north from southern Florida.
Like our native treefrogs, Cuban treefrogs are excellent climbers and will climb high into trees where they sleep during the day. They may also be found closer to the ground in small trees and shrubs. They have even been found buried several inches deep in dry soil. Also like our native treefrogs, Cuban treefrogs are most active at night when they come out from daytime hiding places to feed and reproduce.
Invasive Cuban treefrogs eat a wide variety of food items, including snails, millipedes, spiders, and a vast array of insects. They are predators of several of Florida's native frogs and are cannibalistic. They are also known to eat lizards and even small snakes. Fortunately, several species of native snakes will eat Cuban treefrogs, including rat snakes, black racers, pygmy rattlesnakes, and garter snakes. Owls, crows, and wading birds have also been seen feeding on Cuban treefrogs.
Cuban treefrogs breed predominately in the spring and summer, but in southern Florida they can breed year-round. Reproduction is largely stimulated by rainfall, especially warm summer rains such as those associated with tropical weather systems and intense thunderstorms. The number of eggs deposited by a female is related to her size—larger females lay more eggs. A very large female may lay in excess of 15,000 eggs in one season. Cuban treefrogs are not picky about their breeding sites, as long as the sites lack predatory fish, such as bass and bream. Acceptable breeding sites include isolated wetlands, ditches, decorative ponds, and even swimming pools that are neglected. Cuban treefrogs can breed in surprisingly small amounts of water. An old ice chest or child's wading pool half full of water are suitable nurseries for Cuban treefrog tadpoles to develop into frogs.
Male Cuban treefrogs have a fairly distinct call that sounds like a squeaking door and has also been described as a "snoring rasp". Visit the websites listed at the end of this document to find links to recordings of Cuban treefrog calls. In addition to their breeding calls, individual males will also call from daytime retreat sites to advertise their presence. This "rain call," as it is sometimes called, can be triggered by light rainfall during the day.
Invasive Cuban Treefrogs and Their Impacts in Florida
An invasive species is generally defined as a plant, animal, or microbe that is found outside of its native range, where it negatively impacts the ecology, economy, or quality of human life. Cuban treefrogs fit this definition of an invasive species because they were introduced to Florida by the activities of people and they are causing harm to Florida's natural ecosystems and the quality of life of Floridians. They are also causing economic impacts in some places.
Cuban treefrogs are having negative impacts on Florida's native species and ecosystems. Although they predominately occur around human development, such as urban neighborhoods, Cuban treefrogs are also able to invade natural areas. In both natural and urbanized settings, Cuban treefrogs are known predators of Florida's native treefrogs (Figure 4) and appear to be responsible for declines of some native treefrog species. They also are known to eat several additional species of native frogs, lizards, and many types of invertebrates. Many homeowners in Florida report that Cuban treefrogs appear to have replaced native treefrogs as the dominant frog found around their homes. These same people say that they no longer see native species, such as squirrel treefrogs or green treefrogs, but only Cuban treefrogs. Furthermore, lab experiments (conducted by herpetologist Dr. Kevin Smith) have shown that Cuban treefrog tadpoles are superior competitors with at least two species of native frog tadpoles. Tadpoles of the invasive Cuban treefrog inhibited the growth and development of native southern toad and green treefrog tadpoles. Additional experiments by ecologist Dr. Michael Knight and colleagues showed that survivorship of native squirrel treefrog tadpoles declined significantly in the presence of Cuban treefrog tadpoles. As scientists continue to conduct research on the ecological impacts of Cuban treefrogs, we will develop a better understanding of the effects that this invasive frog is having on Florida's environment.
Human Quality-of-Life Impacts
Cuban treefrogs thrive in human-modified landscapes, such as urban and suburban communities. As a result, they are having impacts on the quality of life of Floridians. Cuban treefrogs seek shelter during the day in tight, enclosed spaces. Homes and buildings provide many of these shelters and abundant sources of food. Because of the combination of abundant places to hide, consistent food sources, and adequate breeding sites provided by human-dominated landscapes, Cuban treefrog populations can become quite dense, and the frogs can become a real nuisance for people.
Cuban treefrogs are "sit-and-wait" predators. On warm nights in Florida, it is common to encounter Cuban treefrogs hanging on walls and windows near lighted areas as they sit and wait for insects (and native treefrogs) to be attracted to the lights. As they feed, they defecate on the windows and walls, and their fecal deposits can become unsightly over time, especially if there are a lot of frogs in the area. Furthermore, when a person enters or exits his or her home at night, Cuban treefrogs that are waiting for an insect meal may be startled and as a result will occasionally jump onto people or into their homes through open doors. This can be a scary experience for a person who is afraid of frogs. Florida's native treefrogs rarely enter homes and buildings and do not cause the problems attributed to Cuban treefrogs.
When they get into homes, Cuban treefrogs can be especially annoying. Cuban treefrogs can enter homes in a variety of ways. They may jump through open doors or windows, be brought into a house inadvertently on an ornamental plant, or get into a home's plumbing system through vent pipes on the roof. When Cuban treefrogs gain access through vent pipes of a home plumbing system they usually end up in a bathroom. There are numerous instances where unsuspecting people have opened the lid to their toilet only to find a bug-eyed Cuban treefrog staring up at them (Figure 5). Cuban treefrogs have also been responsible for clogging sink drains.
Like most frogs, male Cuban treefrogs call to attract mates. When Cuban treefrogs are concentrated in an area for breeding, their calls may be annoying to people who live near breeding sites, especially following heavy rains. Fortunately, the calls of individual frogs are not very loud. (See the list of resources at the end of this document for links to websites where you can hear recordings of Cuban treefrog calls.) Because a single adult female may lay thousands of eggs, and many females will be present in any given pond, you may find numerous gelatinous masses of eggs floating on the surface of a decorative pond or swimming pool after a rainy night in the spring or summer. Left to develop into tadpoles, these egg masses may result in an onslaught of Cuban treefrogs, which, depending on the temperature of the water, can develop and metamorphose into small frogs in as little as 3–4 weeks, further increasing the population of this invasive frog around people's homes.
Cuban treefrogs may also be a nuisance to wildlife enthusiasts that set up nesting boxes to attract and benefit birds. Because Cuban treefrogs prefer enclosed hiding spaces, they readily enter nest boxes erected for birds. Birds may be dissuaded from using nest boxes when they are invaded by Cuban treefrogs (Figure 6), but research is needed to study how the presence of the invasive frogs affects bird use of nest boxes.
Although they are not nearly as toxic as cane toads (also known as the invasive Bufo toad), Cuban treefrogs have a sticky skin secretion that is extremely irritating to the mucous membranes of people, such as the eyes and nose. The secretions cause a burning and itching sensation that can last for more than an hour. This can be especially problematic for people who suffer from asthma or allergies, in which case full recovery from the ill effects of the frog's skin secretions may take several hours. Therefore, it is always a good idea to wash your hands thoroughly after handling a Cuban treefrog. Better yet, wear rubber gloves when handling or attempting to capture Cuban treefrogs. There do not appear to be any documented deaths or serious injuries of pets from ingesting or attempting to eat a Cuban treefrog. However, there are reports of excessive salivation and even seizures by pets that have tangled with these noxious frogs, so dogs and cats should be kept away from them.
Unlike many invasive insect pests and invasive plants, Cuban treefrogs do not currently appear to be having any large-scale negative effects on Florida's economy. Nonetheless, they are known to get into transformer boxes and electrical switches (Figure 7) and occasionally cause short-circuits. This increases maintenance costs for electrical utility companies, and power to some customers in central Florida has been interrupted as a result of short-circuits in disconnect switches caused by Cuban treefrogs. They may also invade electric water pump housings and AC compressor units around residential homes, potentially causing damage. As Cuban treefrog populations continue to expand, this may eventually become a large-scale issue.
What You Can Do
There are several things Floridians can do to help manage invasive Cuban treefrogs and to help scientists at the University of Florida track their spread in the state and elsewhere. You can help advance our knowledge about the geographic distribution of this invasive species by reporting your sightings (see below) of Cuban treefrogs. As Cuban treefrogs continue to expand their range, precise tracking of their status and distribution is imperative for decision-making and resource management. In addition to helping track the expansion of their range, you can also help manage this invasive species in and around your yard. Because Cuban treefrogs eat our native frogs and other wildlife, it is important that we take action to manage them and reduce their negative impacts on our native ecology. Managing Cuban treefrogs will also help reduce their negative impacts on the quality of life of Floridians. Benefits will be greatest in the immediate area around where the frogs are managed (i.e., your yard). See below for suggestions on how to reduce the negative effects caused by Cuban treefrogs on Florida's native wildlife and your quality of life.
Report the Presence of Cuban Treefrogs
It is import to document the locations of Cuban treefrogs in Florida, especially in the panhandle, and elsewhere in the US and Canada. If you see a Cuban treefrog, or suspect you have seen one, outside of peninsular Florida please email Dr. Steve A. Johnson at firstname.lastname@example.org. Include your name, date you saw the frog, where you saw it (state, county, city, street address), and also attach a digital image so Dr. Johnson can positively identify the frog. It is also important to report Cuban treefrog sightings from peninsular Florida (and elsewhere) at EDDMapS, the online mapping system for invasive species in US. Visit https://www.eddmaps.org/ and click the "Report Sightings" tab. Thank you for being a citizen scientist!
Manage Cuban Treefrogs Around Your Home
Because of the destructive effects of invasive Cuban treefrogs on Florida's native species, as well as the problems they cause for people, we recommend that Cuban treefrogs be captured and humanely euthanized. However, before you euthanize a Cuban treefrog, be sure that you are positive about its identification (please visit the UF/IFAS Wildlife website at http://ufwildlife.ifas.ufl.edu/cuban_treefrog_inFL.shtml for identification tips and to see digital images of Cuban treefrogs and native species). At the site you will find lots of helpful information about catching, identifying, and reporting Cuban treefrogs.
To humanely euthanize a Cuban treefrog, you must first capture it; there are several effective methods for doing this. The first is to simply grab the frog from a window, wall, or other perch site. Be sure to wear rubber gloves or use a plastic grocery bag as a glove. Approach quickly and decisively, and with a continuous, swift movement firmly grab the frog (Figure 8).
Another way to capture Cuban treefrogs in order to eliminate them from your property is to attract the frogs to hiding places where they can be easily captured and removed. To do this, simply place short sections of PVC pipe in the ground around your home and garden (Figure 9). Cut 10 foot sections of 1.5-inch-diameter PVC pipe (available at home improvement stores) into approximately three-foot-long sections and push them into the ground about 3–4 inches. Cuban treefrogs may show up in the pipes in a few days, depending on the weather, time of year, and the density of frogs in your immediate area. In some situations it may take several weeks for frogs to find the pipes, so be patient. To remove a frog from a pipe, place a clear sandwich bag over the top end, pull the pipe from the ground, and insert a broom handle or other "plunger" device in the other end to scare the frog into the sandwich bag. (Gently herd the frog and avoid touching it with the plunger.) Once it is in the bag, examine the frog to be sure that it is an invasive Cuban treefrog and not a native species. Euthanize Cuban treefrogs as described below and release native frogs back into the pipe. (PVC pipes provide great artificial habitats for native treefrogs and can help enhance the wildlife value of your garden.) For more details on using PVC pipes to attract treefrogs, see the UF/IFAS fact sheet on making treefrog houses (https://edis.ifas.ufl.edu/uw308).
The easiest way to humanely euthanize a Cuban treefrog is to place the bagged frog into a refrigerator for 3–4 hours then transfer it to a freezer for an additional 24 hours. The initial cool-down period in the fridge acts as an anesthetic to numb the frog so it does not feel any pain when it freezes. Alternatively, you could firmly hold a recently captured Cuban treefrog and apply a benzocaine-containing ointment to the frog's back to chemically anesthetize it before placing it into a freezer to ensure death. To do this, apply a 1-inch stripe of topical benzocaine ointment (Orajel is one popular brand) to the frog's back, rub the ointment around so it covers the back, then after the frog has ceased to move put it in a sealed bag and place in a freezer for 24-hours. After freezing, simply remove the bagged frog from the freezer and dispose of in the trash. Do not use bug spray, sun tan lotion, insecticide, bleach spray, or other household chemicals to euthanize Cuban treefrogs, and never place a live, bagged frog into the trash! Remember to wash your hands thoroughly after handling a Cuban Treefrog to avoid any adverse reaction to the noxious skin secretions of these frogs.
You can also reduce the negative impacts of Cuban treefrogs by eliminating eggs and potential breeding sites. Monitor ornamental ponds for Cuban treefrog egg masses (Figure 10) during the spring and summer, especially after heavy rains. Be sure to check for eggs the morning following rain so the eggs do not have time to hatch. Use a small-mesh aquarium net to scoop out masses of Cuban treefrog eggs floating on the surface of the pond and simply discard them on the ground to dry out. You should also remove Cuban treefrog tadpoles from pools and ornamental fish ponds and euthanize them by cooling then placing in a freezer as described earlier. Properly maintain swimming pools so they are not attractive to Cuban treefrogs, and dump out stagnant water that accumulates in various objects around your yard (e.g., ice coolers, buckets, etc.). This will also help eliminate breeding sites for mosquitoes.
Additional Sources of Information
There are a variety of books, guides, and websites that we recommend for additional information on treefrogs and other amphibians in Florida. These books are available at larger bookstores and online.
Carmichael, P. and W. Williams. 2004. Florida's Fabulous Reptiles and Amphibians. Tampa, FL: World Publications. 120 pp. ISBN: 0-911977-11-2. This is an excellent coffee-table book with wonderful pictures and good information.
Powell, R., R. Conant and J.T. Collins. 2016. Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America. Boston, MA: Houghton Mifflin Company. 494 pp. ISBN: 978-0-544-12997-9. This is the standard field guide for many herpetologists and covers hundreds of species of amphibians and reptiles.
UF/IFAS Extension Florida Wildlife website http://www.wec.ufl.edu/extension/. Click the link to "Wildlife Information," and then find the link to the "Frogs & Toads of Florida" page. In addition to information on Florida's frogs, there are also links to many other useful, wildlife-related resources at the site.
UF/IFAS Department of Wildlife Ecology and Conservation website http://ufwildlife.ifas.ufl.edu/. Click the links for "Florida's Frogs," "Invasive Cuban Treefrog," and "Become a Citizen Scientist." This website contains images and identification tips for of all of Florida's frogs as well as access to recordings of the calls of the species, including the Cuban treefrog.