1. Galls of some species of cynipid wasps produce a sugary secretion that attracts ants, which are thought to defend gall‐inducers against natural enemies, although evidence in support of this hypothesis is mixed. Some discrepancies may be explained by the complexity of the multitrophic interactions, which involve multiple ant and parasitoid species, and which are influenced by gall size and aggregation. The gall exudate also affects these relationships, although secretion patterns and possible host plant impacts appear to be unstudied.2. We studied Disholcaspis eldoradensis Beutenmuller (Hymenoptera:Cynipidae) galls on Quercus lobata Née (Fagaceae) and its interactions with ants and parasitoids. We used exclusion experiments to test the defensive benefits of ants and timing of parasitoid oviposition, and we measured how gall size, aggregation, and ant visitation influence these interactions. In addition, we measured variation in sucrose secreted by galls during larval development.3. Ants benefited gall inducers in 2018, but not 2019. Over 80% of visits observed were from invasive ants. Gall aggregation was not associated with parasitism, gall inducer success, or visitation by ants. During 2018, gall size was inversely correlated with the chance of parasitism and positively correlated with gall inducer biomass, whereas in 2019, parasitoid community composition varied with gall size. Sucrose secretion varied widely among galls and through time.4. Facultative mutualisms between ants and sugar‐secreting galls are complex and likely vary through time depending on local ecological circumstances. Gall secretions warrant increased attention and may impose a substantial burden on some host plant photosynthetic budgets.