Simple SummaryThe peach fruit moth, Carposina sasakii, and the oriental fruit moth, Grapholita molesta are two co-occurring pests in orchards. Larvae of both species bore into fruits and cause damage to fruit production. Understanding the gut microbes, as well as the influencing factors between these co-occurring pests, may provide insight into their occurrence and control. In this study, we found that the two pests shared many bacteria in their gut from the genera Pseudomonas, Gluconobacter, Acetobacter, and Pantoea. The composition of the gut microbiota is similar between the two species collected from the same host plant and orchard; however, the gut microbiota of individuals collected from different orchards of the same host plant can be different within pest species. These results show that the two fruit moth pests have similar gut bacteria and varied environment in orchards can influence their gut microbiota.Numerous gut microbes are associated with insects, but their composition remains largely unknown for many insect groups, along with factors influencing their composition. Here, we compared gut bacterial microbiota of two co-occurring agricultural pests, the peach fruit moth (PFM), Carposina sasakii, and the oriental fruit moth (OFM), Grapholita molesta, collected from different orchards and host plant species. Gut microbiota of both species was mainly composed of bacteria from Proteobacteria, followed by Firmicutes. The two species shared bacteria from the genera Pseudomonas, Gluconobacter, Acetobacter, and Pantoea. When we compared two pairs of PFM and OFM populations collected from the same host species and the same orchard, there is no difference in alpha and beta diversity in gut microbiota. When we compared gut microbiota of the same species and host plant from different orchards, alpha and beta diversity was different in populations of PFM collected from two pear orchards but not in other comparisons. Our study suggests that the two pests share many features of gut microbiota and environment in orchards is a main factor influencing their gut microbiota.