Trees are a major nuisance for farmers. They soak up sunlight, water, and soil nutrients that could be going to crops instead. But it turns out that sunflowers and fava beans actually benefit from having a forest near at hand. The closer these and other flowering crops are to forest edges, the more wild bees can reach and pollinate them, finds a study published this month in Ecology and Evolution. Researchers captured wild bees in fields of oilseed rape—harvested for vegetable oil and biodiesel—growing near forest edges. They enticed the insects with yellow, ultraviolet-painted pan traps that mimicked flowers. As the bees flew in expecting a meal, they became caught in the water lining the pans. The deeper the researchers moved into the fields, the fewer bees they found in the traps. The bees that did turn up were larger than those found closer to the forest, indicating that many are too small to make it to crops at the heart of the field. Bee populations worldwide are declining, but farmers can help the insects thrive by protecting forest edges near their crops. The best edges are untidy, merging gradually into the field, with scrubby bushes and brambles.