[Aim]  To investigate if the island area and island edge effects caused by habitat fragmentation can have a “bottom-up impact” on the distribution and structure of the cynipid gall wasp community. [Methods]  Twelve sets of functional leaf traits for Quercus fabri and Q. serrata were measured from sample belts interori and on the edge of different sized islands in Thousand Island Lake. The influence of the area effect and edge effect on the gall wasp community was analyzed using the combined number of gall wasps on host plants from all the sample belts. [Results]  (1) There was no difference in the distribution densities of Q. fabri or Q. serrata between the interior and edge transects for the different sized islands (P>0.05). (2) The nitrogen content of Q. fabri and the chlorophyll content of Q. serrata showed a significant positive correlation with island area (P<0.05), while the leaf dry weight of Q. fabri and the leaf thickness of Q. serrata were significantly negatively correlated with island area (P<0.05). However, there was no significant difference in leaf functional traits between the island edge and the interior for either species (P>0.05). (3) The gall wasps present on Q. fabri and Q. serrata all belonged to the genus Andricus, of these three species were found on Q. fabri and five species on Q. serrata. (4) There was no difference in the number of gall wasp galls between the interior and edge island sample belts (P>0.05). However, the number of galls increased with island size. Gall wasp number was significantly positively correlated with the leaf nitrogen content, leaf area, and specific leaf area of Q. fabri (P<0.05), and with chlorophyll content, leaf area, and specific leaf area of Q. serrata (P<0.05). In contrast, gall wasp number was significantly negatively correlated with leaf tissue density (P<0.05) and significantly positively correlated with the first principal component for both tree species (P<0.05). [Conclusion]  The island edge effect, resulting from habitat fragmentation, did not have an obvious effect on the community structure or distribution of gall wasps. However, the island area effect influenced gall wasps by affecting their host plants. Gall wasp host preference for egg-laying and gall formation is related to the ability of host plants to utilize light resources.