Slugs and snails are parasitised by a range of organisms including nematodes, bacteria, microsporidia, mites and flies (Barker, 2004). Of these, the nematodes are the most numerous and diverse as 108 species have evolved to parasitise molluscs (Grewal et al., 2003). One of these nematodes (Phasmarhabditis hermaphrodita) is a lethal parasite of a range of pestiferous slugs and snails including Deroceras reticulatum, Arion ater and Helix aspersa (Wilson et al., 1993). P. hermaphrodita has been formulated into a biocontrol agent (Nemaslug®) by Becker Underwood-BASF available for farmers and gardeners (Rae et al., 2007). Nematodes are mixed with water and applied using spraying equipment to soil where then go and search for potential gastropod hosts. They are attracted to slug mucus and faeces (Rae et al., 2006, 2009) and upon discovery they penetrate through the slugs’ mantle and kill it between 4 and 21 days (Wilson et al., 1993; Tan & Grewal, 2001).