Pollination and pest control are important in many agroecosystems. Beneficial insects that provide these services (e.g., bees and natural enemies) often require floral resources beyond crop bloom. Planting floral resources along crop field margins may be a useful tactic to support communities of beneficial insects in agroecosystems. We examined the effect of planting buckwheat (Fagopyrum esculentum Moench) along lowbush blueberry (Vaccinium angustifolium Aiton) field margins on beneficial insect abundance and generic richness. We found that bee abundance was higher in buckwheat transects than control transects in 2014 and 2015, but not 2016, and that bee generic richness was higher in buckwheat transects than in control transects in 2015 only. High variability occurred across years. All bee genera recorded during blueberry bloom were also collected in buckwheat transects, suggesting buckwheat is a useful resource for the bee community involved in blueberry pollination. The effect of buckwheat on natural enemies was variable and inconsistent. We conclude that buckwheat influenced bee and natural enemy communities during certain years, but field edges in the lowbush blueberry fields studied may already adequately support beneficial insects. Thus, not all habitat management efforts with augmentative floral plantings may consistently boost communities of beneficial insects.