In our paper 'Rapid functional response tests for assessing impacts of alien snails on food crops' (10.1016/j.ecolind.2020.107138 ), we used lab-derived data of consumption of crops by terrestrial snails to construct functional responses (FRs). The use of comparative functional response tests could give insight in the potential impact of alien herbivorous snails on agricultural crops and natural vegetation. It has been hypothesised that invasive alien snails are superior competitors for resources in comparison with common native species, due to higher attack rates and lower handling times of their food. In our study, food consumption of Cornu aspersum differed significantly for three crops: lettuce (Lactuca sativa), endive (Cichorium endivia var. latifolia) and common corn salad (Valerianella locusta). The functional responses for consumption of Lactuca sativa differed significantly between individuals collected from wild and from cultured populations of C. aspersum. Furthermore, the food consumption (in dry weight) of C. aspersum differed between tests with presence of an intraspecific and interspecific competitor (i.e., C. aspersum and Cepaea nemoralis, respectively). So, the interspecific and intraspecific competition for resources should be considered in risk assessments in order to generate more reliable impact predictions of alien snail species and to improve our understanding of their interactions with other grazers. In this repository, we provide the data of the consumption of these three different crops by Cornu aspersum originating from wild and from cultured populations . Furthermore, the data concerning the effect of a competitor on the consumption of lettuce is included.This dataset includes the following two data files:1. 'Functional_Response_All_data' includes all the data collected from functional response tests of Cornu aspersum individuals from cultured and wild populations feeding on three different type of crops.2. 'Competition_experiment_All_data' is a dataset including all the data concerning the potential impact of the presence of a competitor on lettuce consumption by Cornu aspersum.In both data sets weight and length of the snails is also provided.