At one time or another, almost every alfalfa field in the Midwest and eastern areas of the U.S. and Canada has suffered from leafhopper infestation. It is common for alfalfa growers to mistake leafhopper damage for moisture or heat stress, or Boron deficiency due to the characteristic yellowing symptom caused by leafhopper damage. Adult potato leafhoppers are yellowish or lime green, and about 0.13 inch long and 0.03 inch wide. The nymphs are similar in appearance, but lack wings. Both adult and nymph stages cause damage to alfalfa.
Leafhoppers normally jump or crawl rapidly sideways when disturbed.
Leafhoppers are sucking insects and feed on the sap from alfalfa plants and cause yellowing and stunts plant growth. Very young alfalfa plants and plants in early stages of regrowth are the most susceptible to leafhopper damage. Infestation is most likely to occur prior to the second and third cutting of alfalfa in most areas, and in the first cut if it has been delayed. Warm, dry spring weather is much more conducive to leafhopper infestation than is cool, wet spring weather. Damaging populations may be more likely when temperatures are between 70 and 90 F., and particularly when harvest is delayed.