The Bipalium genus is made up of a variety of large, predatory, terrestrial planarians or flatworms.  Some species have a distinctive head shape leading to them often being referred to as hammerhead worms.  These species are native to tropical and subtropical areas of Southeast Asia and likely hitchhiked to North American in soil and plant materials.  They are active predators of invertebrates such as snails or slugs and feed particularly on earthworms.  With the extensive spread of invasive Asian Earthworms there is a ready food source for these species of flatworms and it is likely that they will continue to spread.  They depend on humid soil environments and mostly feed at night.  These species are not directly harmful or parasitic to humans or pets but can cause skin irritation when handled and can cause illness in pets if consumed.

Recently, New Jersey has been receiving reports and observations of two species of invasive planarian; Bipalium adventitium, a hammerhead worm, and Platydemus manokwari, a New Guinea Flatworm.  Both species are easily identified from photographs and generally there are no similar native species to cause identification confusion. 

As mentioned before, they are not harmful to humans but can pose a hazard to pets should they consume them or if handled.  It is recommended to only handle them while wearing gloves.  Generally, they are found in damp soil environments such as under leaves, rocks or debris or on the soil surface at night, reducing the chance of contact with pets.  However, if you identify these species in your yard, extra care should be paid to monitor your pet’s activities to avoid them consuming them.  There are very limited means for controlling planarians other than careful collection and bagging while wearing gloves or direct application of salt, boric acid, vinegar, or citrus oil to the worm.