These spottings make it worthwhile to discuss spittlebugs. The spittle masses found in alfalfa fields were created by the nymphs, which require a moist environment to survive. These insects have piercing-sucking mouthparts with which they extract fluids from the plants. Nymphs typically are present for 5 to 8 weeks, depending on the temperature. Although spittle masses may seem prevalent in some fields, don't overreact to their presence.
Spittlebugs infrequently cause economic damage in alfalfa.
However, if their numbers exceed one per plant, which is an exceptionally large population, they can cause yield losses.