[Objectives]  To determine whether mass-flowering plants in greenhouses in cold regions provide nutrition for adult insects is an important issue related to the effective control of arthropod pests. [Methods]  The planting structure, species of flying adult insects captured on sticky card traps, influence of planting ratio (mass-flowering plants to other species) on pest abundance and parasitoid abundance were investigated in three independent, large, glass greenhouses in a suburb of Harbin city (Latitude 45°N) in 2010-2011. Predator abundance and the relationship between parasitoids and predators and between pest abundance and diversity were analyzed using linear regression models. [Results]  The results show that, at least inNorthern China, higher ratios of mass-flowering plants can increase the biodiversity of pests and suppress outbreaks of specific pest species in greenhouses. Monocultures of specific mass-flowering plants can, however, also lead to serious pest infestation, and fewer parasitoids and predators. Parasitoids and predators responded to environmental conditions in a similar way, except that predators, which are typically larger than parasitoids, were more sensitive to crop management, especially chemical spraying. [Conclusion]  This study provides primary information to inform the choice of plants for “bio-control engineering” of open fields. The methods used can also provide early warning of the invasion of exotic organisms and global change in arthropod biodiversity.