New Guinea Flatworm
The New Guinea flatworm (Platydemus manokwari) is a predatory, terrestrial flatworm. This flatworm averages 1.5 to 5 inches in length and has a shiny, dark brown/black body with a pale stripe running down the middle, though the stripe may not be visible in bright light. The underside is pale grey to pinkish beige and the long, snout-like head has two eyes that sit back from the pointed tip.
New Guinea flatworms are considered nonnative in Florida and can be found in potted plants, under rocks, and in leaf litter and other substrates in moist, dark areas. After heavy rainfall, this mostly nocturnal invertebrate emerges and may come out from under foundations and crawl up walls.
New Guinea flatworms reproduce sexually, producing cocoons that contain 3 to 9 embryos and which will hatch after approximately 8 to 10 days. Juveniles reach maturity approximately three weeks after hatching.
Researchers have observed New Guinea flatworms preying upon land snails, earthworms, slugs and other small invertebrate animals.
New Guinea flatworms are native to New Guinea, an island north of Australia and south of the equator.
The first recorded observation of New Guinea flatworms in the mainland Americas occurred in Miami-Dade County in 2012. As of July 2017, the FWC has received reports of New Guinea flatworms from over 40 counties in Florida.
New Guinea flatworms feed on snails and other terrestrial invertebrates. These flatworms are known land snail predators in Japan and have also caused the decline of Hawaiian tree snails in Oahu, Hawaii. New Guinea flatworms can potentially consume native snails in Florida, including threatened and imperiled species.
New Guinea flatworms are a potential host for the rat lungworm parasite which can be transmitted to humans, however, no cases of rat lungworm infection in humans have been confirmed in Florida. The lungworm parasite can also be carried by native species such as snails, slugs, and freshwater shrimp, crabs and frogs. While New Guinea flatworms pose a potential health threat, they are no more dangerous than the native species of invertebrates that can carry the rat lungworm parasite. Humans are unlikely to be affected by the rat lungworm parasite since transmission of the parasite can only occur through ingestion. Eating raw or undercooked snails or slugs or raw produce that contains small snails or slugs is the most common method of infection in humans. New Guinea flatworms may regurgitate stomach contents upon handling, causing skin irritation. Direct handling of the flatworm should be avoided to prevent the possibility of parasite transmission and to avoid skin irritation from their stomach secretions.
New Guinea flatworms are not regulated by the FWC, and no permit is required to import this species or transport specimens within the state. Exportation of New Guinea flatworms from Florida into another state may require a USDA/APHIS Plant Protection and Quarantine 526 permit. People should contact their local USDA/APHIS office or call the USDA/APHIS Customer Service Call Center at 844-820-2234 to inquire about permit requirements if they intend to export New Guinea flatworms or soil containing New Guinea flatworms to another state.
Frequently Asked Questions
New Guinea flatworms are not protected in Florida and the FWC encourages people to remove this nonnative species on their own property. The FWC is aware that New Guinea flatworms have spread to many parts of Florida, and people do not need to report sightings from counties where the species has already been observed. However, reports from counties where this species has not yet been observed are useful to researchers and should be reported online at IveGot1.org. To see if New Guinea flatworms have been reported from a certain county, check the county distribution map online at https://www.eddmaps.org/florida/distribution/uscounty.cfm?sub=78294.
New Guinea flatworms are not a protected species in Florida, and property owners may treat soil on their own property in natural areas and in potted plants that contain flatworms by soaking with hot water (between 109-120 degrees Fahrenheit) for five minutes. This method has been shown to kill flatworms without damaging the roots of plants. New Guinea flatworms may also be quickly and humanely killed by pouring boiling water directly onto the worm.
Commercial pesticides have been tested against other species of flatworm, and only gamma-HCH (Lindane), a broad-spectrum insecticide, provided significant chemical control. However, this insecticide is not considered to be suitable for widespread control measures for terrestrial flatworms (Justine et al., 2014; Cannon et al., 1999).
New Guinea flatworms are a potential host for the rat lungworm parasite which can be transmitted to humans; however, no cases of rat lungworm infection in humans have been confirmed in Florida. Native species such as snails, slugs, and freshwater shrimp, crabs and frogs can also carry the rat lungworm.
If you plan to handle New Guinea flatworms, slugs, or snails, wear gloves. If you have handled New Guinea flatworms, slugs, or snails with bare hands, wash your hands carefully. Fruits and vegetables that are to be eaten raw should be washed thoroughly. More information about the rat lungworm and preventing infection may be found at the Centers for Disease Control and Prevention (CDC) website and at https://www.youtube.com/watch?v=V_f1IK93ZtE.
If your pet comes into physical contact with a New Guinea flatworm, clean the area of contact with soap and warm water. New Guinea flatworms have the potential to carry the rat lungworm parasite, which can affect pets. The rat lungworm can only be transmitted by ingestion, so if your pet consumes a New Guinea flatworm, monitor your pet and seek veterinary help if any signs of lungworm occur. Native species such as snails, slugs, and freshwater shrimp, crabs and frogs can also carry the rat lungworm, so pet owners should be aware of the signs of lungworm if their pet consumes these types of animals.
The number of New Guinea flatworms present on a property varies by location. Some people have observed additional flatworms on their property after the initial sighting, while others only observe a single flatworm. New Guinea flatworms are most active at night and after a rain, so people are less likely to see flatworms on their property during the day.
The FWC is aware of New Guinea flatworm observations in 40 counties but is not conducting site visits.
Cannon, R. J. C., R. H. A. Baker, M. C. Taylor, and J. P. Moore. 1999. A review of the status of the New Zealand flatworm in the UK. Annals of Applied Biology 135: 597-614.
Justine, J. L., L. Winsor, D. Gey, P. Gros, and J. Thévenot. 2014. The invasive New Guinea flatworm Platydemus manokwari in France, the first record for Europe: time for action is now. PeerJ 2(e297). <http://doi.org/10.7717/peerj.297>. Accessed 4 Oct. 2018.
Kern, B. 2016. The New Guinea Land Planarian, A New Invasive Species. Ft. Lauderdale Research and Education Center, Davie, Florida, USA.
Ohbayashi, T., I. Okochi, SATO Hiroki, and T. Ono. 2010. Food habit of Platydemus manokwari De Beauchamp, 1962 (Tricladida: Terricola: Rhynchodemidae), known as a predatory flatworm of land snails in the Ogasawara (Bonin) Islands, Japan. Page 35-40 in K. Kawkami and I. Okochi, editors. Restoring the Oceanic Island Ecosystem. Springer, Tokyo, Japan.
Sugiura, S. 2010. Prey preference and gregarious attacks by the invasive flatworm Platydemus manokwari. Biological Invasions 12(6):1499-1507.