They go through five stages, or molts, in about two weeks before they become adults. The entire life cycle takes a little longer than three weeks. We do not yet have a reliable method to forecast damage by the leafhopper because damage relates to the density of the leafhopper and the age and state of the stand at the time of infestation. We do know that very early detection of the leafhopper before damage appears is essential for good management. Very young plants and plants in very early stages of regrowth are the most sensitive to leafhopper damage.
Damage is intensified by moisture stress during drought.
In general, if the alfalfa plant is more than 14 inches tall before the leafhopper begins feeding on it, no reduction in yield will result. If leafhoppers infest the alfalfa regrowth when it is 2 to 4 inches tall, however, densities as low as one per sweep can cause economic damage under the right circumstances. Potato leafhopper damage is intensified by drought. Under severe drought conditions, where dry weather conditions are expected to continue, leafhopper action thresholds can be halved, especially for new seedings. While walking forward, swing the net into the tops of alfalfa stems using a pendulum motion.