Biodiversity in agricultural landscapes has declined significantly due to intensified farming practices, underscoring the need for sustainable pest management. Here, we tested whether in-field flowering strips can be an alternative to conventional insecticide use in farming systems. We experimentally manipulated flowering strip mixtures on 10 sites across Germany and measured aphid infestation, biocontrol, and yield in sugar beet, a key European sugar source. All flower mixtures reduced aphid populations more effectively than controls without flower strips, with some mixtures performing as well as insecticides. Mixtures containing legumes were particularly effective against aphids, likely due to their attraction of specific predators. Sugar yields were similar in all plots, regardless of flower mixtures or insecticide treatment. Synthesis and applications: Our findings indicate that in-field flower strips or derived legume-based intercropping systems can help reduce reliance on pesticide use in agriculture.