Phasmarhabditis papillosa is a promising biocontrol agent of gastropods in crops. To enhance the efficacy of mollusc parasitic nematodes, a better understanding of the chemical signalling between hosts and parasites is needed. The objective of this research was to test the stimulus–response behaviour of the mollusc parasitic nematode P. papillosa towards mucus of the following mollusc species: Arion vulgaris, Limax maximus, Deroceras reticulatum, and Helix pomatia. The nematode chemotactic response was observed as directed motility towards mucus of the tested mollusc species at two temperature regimes under laboratory conditions. The motility of P. papillosa was more strongly expressed at a higher temperature (20 °C) than at a lower temperature (15 °C). When comparing mucus of different mollusc species, none of the tested molluscs significantly affected the directed motility of P. papillosa at the lower temperature (15 °C). At the higher temperature (20 °C), mucus samples from L. maximus and H. pomatia were observed to be more attractive than those from A. vulgaris or D. reticulatum for the nematodes. Our results indicate that P. papillosa distinguishes among mollusc species by exhibiting a chemotactic response to a signal emanating from mollusc mucus.