Phasmarhabditis hermaphrodita is a species of roundworm that is classified within the Nematoda phylum. This species is found in soils where slug species from the Limacidae, Arionidae, and Milacidae families are located, with one common host being Deroceras reticulatum. The worm can be located in soil by using real-time PCR testing methods, a test that also distinguishes it from its similar relative, Phasmarhabditis neopapillosa.
The life cycle of Phasmarhabditis hermaphrodita begins in soil, when young larvae have bacteria living in their stomachs. These bacteria are important for the survival of the larvae once they locate and enter a suitable slug host, because they provide a source of food to the developing worms. When the larvae have reached the shell cavity of the slug, the bacteria are released, allowing the larvae to feed on a stable source of food. These bacteria cause harm to slug by giving it septicaemia, a condition in which the slug swells in the mantle area and feeds less frequently. Four to twenty-four days after the initial infection, the slug dies. The larvae must remain within the snail long enough to mature and breed. To do this, it is thought that the larvae are able to modify the slugs movements so it remains protected underneath the soil even after it dies.
Because of its dependence upon plant eating slugs, many farmers use Phasmarhabditis hermaphrodita as a molluscicide in controlling slug populations, instead of unnatural pesticides like carbamates or metaldehyde. The worm is raised in a culture, along with the Moraxella osloensis bacterium it uses to feed. It is recommended that farmers use the molluscicide in damp soil that is up to sixty-eight degrees Fahrenheit. The parasite is effective before it even kills its slug hosts, because it stops the slug from feeding. Plants are protected for up to six weeks by using this method.