Which of the following is not a method for controlling leafhoppers?

Soaking plants in water is not an effective method for controlling leafhoppers. While it may seem like a way to wash off some insects from the plants, it does not address the underlying issue of infestations or prevent future ones. Leafhoppers can fly and may simply return after the plants dry. Additionally, soaking plants could harm them, especially if they are sensitive to excess moisture or if it leads to fungal diseases.

In contrast, using insecticidal soap is a recognized method for controlling soft-bodied insects by suffocating them. Adding beneficial insects that prey on leafhoppers can naturally reduce their population, and using pheromone traps is a proactive strategy to monitor and capture these pests. Each of these methods targets leafhoppers effectively, making them reliable choices in integrated pest management strategies.