Consumption of infected plant tissues by decomposing organisms is an important part of ecosystem services. We tested how the common woodlouse (Porcellionides pruinosus, Isopoda: Oniscidea) may contribute to the decomposition process in a laboratory experiment in which Mycosphaerella pyri-infected pear leaves with or without the aecia of Gymnosporangium sabinae were offered as food. We recorded the loss of healthy and infected leaf tissues. Isopod survival rate was also monitored. We found (1) a certain pattern of preference in the consumption of infected leaf material; and (2) that the presence of G. sabinae reduced leaf consumption but had no effect on the ingestion of Mycosphaerella-infected spots; and (3) the mortality of P. pruinosus was adversely influenced by G. sabinae, but the results were highly dependent on confinement conditions. Our results suggest that woodlice consume plant pathogenic fungi, and therefore offer the ecosystem service of neutralizing infective plant remnants during decomposition.