Trap cropping uses alternative plants to attract pests away from a main crop. For example, nasturtium (Tropaeolum majus) is a food plant of some caterpillars which feed primarily on members of the cabbage family (brassicas); some gardeners claim that planting them around brassicas protects the food crops from damage, as eggs of the pests are preferentially laid on the nasturtium. However, while many trap crops divert pests from focal crops in small scale greenhouse, garden and field experiments, only a small portion of these plants reduce pest damage at larger commercial scales.