Microsatellites were developed for two pest slug species: self-fertilizing Arion intermedius and outcrossing Deroceras reticulatum. Six microsatellites from each species were tested on individuals collected from within and between arable fields. The 39 individuals analysed per species had 3-9 and 7-26 alleles per microsatellite for A. intermedius and D. reticulation, respectively. Gene diversity, [1 - Sigmap(i)(2)], ranged from 0.19 to 0.75 and 0.74 to 0.95, respectively.