Spittle bugs are the nymphs of an insect related to leafhoppers known as frog hoppers. They hatch from eggs laid in late summer that overwinter on susceptible plant stems and debris. The nymphs secrete the froth to protect themselves from predators, provide insulation from temperature extremes and to keep themselves from drying out.
The nymphs feed by sucking the plant juices. Damage to the host plant is usually negligible and the use of sprays is not warranted. Hosing off the affected plants with water is all that is needed to control them. It takes about 5 weeks for the nymphs to become adults at which time, the “spit” will disappear. Very rarely, thick infestations can cause distortion of new growth and stunting. If so, Rose Defense or Bonide 3 Rx will bring them under control.