This file contains the tabulations of insects sampled from native and non-native plants. The methods involved were as follows: Phytophagous insects were collected on native and non-native plants in two areas: Haren, province of Groningen, the Netherlands (53º10’N 06º36’E) and Sendai, Miyagi prefecture, Japan (38º16’N 140º52’E). In total, 47 plant species were sampled, which could be divided into four groups: (1) plant species native to the Netherlands and non-native to Japan, or vice versa (14 spp.), (2) plant species non-native to both areas (5 spp.), (3) plant species studied only in the Netherlands; either native or non-native (9 spp.), and (4) plant species studied only in Japan; either native or non-native (19 spp.). Most data were collected simultaneously in both areas between late April and early August, 2010. Only the data on the level of herbivory were not collected simultaneously. Insect collection took place in forests, parks, and gardens. In both the Netherlands and Japan the same two ...