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A new state record of Bipalium adventitium Hyman, 1943 (Tricladida: platyhelminthes) from Idaho, with a key to the species of Bipalium known to inhabit the United States.


Bipalium adventitium is reported for the first time from Idaho. This species has been previously recorded from California, Connecticut, Illinois, Massachusetts, Maryland, Michigan, New York, Ohio, Pennsylvania, Tennessee, Washington, and West Virginia, and is considered to be widespread throughout the northern United States. The population appears to have overwintered, suggesting that B. adventitium may become established in Idaho. Species of Bipalium known to occur in the United States are keyed and figured.

KEY WORDS: Bipalium adventitium, Idaho, introduction


The terrestrial flatworm Bipalium adventitium Hyman, 1943 has been introduced throughout northern North America (Ducey, et al., 2005; Ducey, et al., 2007). The preponderance of records from the northeastern United States likely stems from the scope of previous sampling efforts, and is not an accurate portrayal of the actual range or recent range expansions of B. adventifium (Ducey, et al., 2005). This species was originally described from Berkeley, California (Hyman, 1943), though it is prBipaliumative to Asia (Fiore, et al., 2004, Zaborski, 2002). It is generally believed that B. adventitium, as well as the other Bipalium found in North America, has been inadvertently dispersed into and around North America by the movements of plants and soil in the horticultural industry (Zaborski, 2002). Ducey and Noce (1998) suggested that B. advenfitium could also have been introduced with commercially produced earthworms discarded by fishermen.

All members of the genus Bipalium are predatory (Ducey, et al., 2007). B. adventitium preys on terrestrial oligochaetes (Ducey and Noce, 1998), which it hunts by chemoreception (Fiore, et al., 2004). Klots (1960) noted that B. aventitium fed on oligochaetes, as well as "slugs, insect larvae and the like", though Ducey and Noce (1998) found that B. adventitium rejected slugs and larval Tenebrio in laboratory trials. B. advenfitium preys upon a wide variety of earthworm species, and can subdue specimens 55 times their own mass (Zaborski, 2002).

Other predatory terrestrial planarians introduced to other continents have had effects on earthworm populations and soil ecology (Ducey, et al., 2007; Ducey, et al., 2005). It is hypothesized that B. adventitium may be having a similar effect in North America (Ducey, et al., 2007; Ducey, et al.,2005). B. adventitium has been previously recorded from California, Connecticut, Illinois, Massachusetts, Maryland, Michigan, New York, Ohio, Pennsylvania, Tennessee, Washington, and West Virginia (Ducey et al., 2005).

A homeowner from Lewiston, Nez Perce County, Idaho found a single specimen of B. adventitium under a rock in a landscaped back yard on 24 March 2010. Two more specimens were collected under the same rock on 31 March, and were brought to the Nez Perce County Agricultural Extension agent, who forwarded them to the William F. Barr Entomology Museum, University of Idaho, Moscow. An additional specimen was noted by the same homeowner under landscaping fabric approximately 10m away from the first site during the second week of April. The two specimens were preserved in 70% ethanol, deposited in the William F. Barr Entomology Museum and identified by one of us (MAH) using Hyman, 1943 and Ducey, et al., 2007.

Further discussion with the homeowner revealed that the back yard had been extensively landscaped every spring since 2007. The majority of plants were acquired from local nurseries. In 2009, plants were added that were acquired from two nurseries in western Washington. The fact that no landscaping had occurred in 2010 prior to the collection suggests that the specimens found had overwintered, and that B. adventitium could become established in Idaho.


Bipalium is readily identified by its elongate (80-300mm) body, expanded, lunate head, and lateral rows of numerous eyespots (Klots, 1960; Hyman, 1943). The expanded, lunate head can retract during preservation, but the distinctive rows of eyespots usually remain apparent (M. Hill, pers. obs.). This key only covers the species of Bipalium that have been previously recorded from the United States. Bipalium kewense Moseley, 1878 are common in greenhouses (Hyman, 1943), and are found outdoors in southern states and California. B. adventitium is widespread throughout the northern half of the country (Ducey, et al., 2005; Ducey, et al., 2007). Bipalium cf. vagum Jones and Sterrer, 2005 has been found in Texas and Florida, and is likely to be found in other Gulf States (Ducey, et al., 2007). Bipalium pennsylvanicum Ogren, 1987 is only known from two sites in Pennsylvania (Ducey, et al., 2007; Ogren, 1987). All Bipalium species in the United States are typically found in urban and suburban areas (Ducey, et al., 2007). The species are illustrated in Figure 1.

1a. Dorsum with a single dark longitudinal stripe    B. adventitium
1b. Dorsum with three or more dark longitudinal
    stripes                                          2
2a. Dorsum with five longitudinal stripes            B. kewense
2b. Dorsum with three longitudinal stripes           3
3a. Dark, transverse band directly posterior of
    head present                                     B. cf. vagum
3b. Dark, transverse band directly posterior of
    head absent                                      B. pennsylvanicum


The authors wish to thank Michelle Schmidt, the homeowner who found the B. adventitium in her back yard. The authors also wish to acknowledge Mary Busch, Horticulture Associate at the Nez Perce County University of Idaho Extension, and Dr. Ed Bechinski, Professor of Entomology and IPM Extension Coordinator, who forwarded the specimens on to the authors. The authors also wish to thank D. Christopher Rogers and two anonymous reviewers for their helpful comments on this paper.


Ducey, P.K., McCormick, M., Davidson, E. 2007. Natural history observations on Bipalium cf. vagum Jones and Sterrer (Platyhelminthes: Tricladida), a terrestrial broadhead planarian new to North America. Southeastern Naturalist 6:449-460.

Ducey, P.D., Noce, S. 1998. Successful invasion of New York State by the terrestrial flatworm Bipalium adventitium. Northeastern Naturalist 5:199-206.

Ducey, P.K., West, L.J., Shaw, G., De Lisle, J. 2005. Reproductive ecology and evolution in the invasive terrestrial planarian Bipalium adventitium across North America. Pedobiologia 49:367-377.

Fiore, C., Tull, J.L., Zehner, S., Ducey, P.K. 2004. Tracking and predation on earthworms by the invasive terrestrial planarian Bipalium adventitium (Tricladida, Platyhelminthes). Behavioral Processes 67:327-334.

Hyman, L.H., 1943. Endemic and exotic land planarians in the United States with a discussion of necessary changes in the Rhynchodemidae. American Museum Novitates 1241:1-21.

Klots, A.B. 1960. A terrestrial flatworm well established outdoors in the northeastern United States. Systematic Zoology 9:33-34.

Ogren, R.E. 1987. Description of a new three-lined land planarian of the genus Bipalium (Turbellaria; Tricladida) from Pennsylvania, U.S.A. Transactions of the American Microscopical Society 106: 21-30.

Zaborski, E.R. 2002. Observations on feeding behavior by the terrestrial flatworm Bipalium adventitium (Platyhelminthes: Tricladida: Terricola) from Illinois. American Midland Naturalist 148:401-408.

by Matthew A. Hill (1,3) and Frank Merickel (2)

(1) EcoAnalysts, Inc., Moscow, Idaho (2) William F. Barr Entomology Museum, University of Idaho, Moscow (3) Corresponding author, email:
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Article Details
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Author:Hill, Matthew A.; Merickel, Frank
Publication:Journal of the Idaho Academy of Science
Article Type:Report
Geographic Code:1USA
Date:Jun 1, 2011
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