Many species of hover fly larvae feed on aphids. Scientific evidence that the planting of flowers attracts hover fly adults exists for other regions, including the United Kingdom, New Zealand and California, said Colley. In the experiments, Colley and Luna found alyssum to be the most effective attractant to adult hover flies and the parasitic wasps. There isn't an instant result as with using a pesticide. You don't measure the effects the next day.
Biological control affects a whole cycle of life over time.
It's a long-term solution. The research still requires several more years of work before specific recommendations can be made to growers, stressed Luna. However, broccoli grower Bill Chambers, who collaborated with Colley and Luna, was impressed. The amount we have spent on interplanting has been minimal compared with the amount we would have spent on increased use of pesticides. And we are enhancing biological diversity.