Jerry Brust, IPM Vegetable Specialist, University of Maryland; jbrust@umd.edu
Many strawberry growers have seen the meadow spittlebug (Philaenus spumarius) in their strawberries this year. Some of these growers include high tunnel growers who have never seen spittle bugs before in their high tunnel strawberries. The spittlebug is an annoying pest on strawberries that under extremely high numbers can stunt plants and reduce berry size. But they are more of a nuisance especially to u-pick growers as the pickers object to being wetted by the insect excretion (the spittle, even though it is harmless).
Spittlebugs can be recognized by the white masses of foam found on leaves, petioles, and stems of plants (Fig. 1). The yellow-green nymphs produce this covering to protect themselves from predators and desiccation. Initially the nymphs feed at the base of the plants, but later move up to more tender foliage. Feeding may cause leaves to become wrinkled and dark-green. Although fruit may be stunted under heavy spittle bug populations, yield loss rarely occurs. High spittlebug populations are often correlated with weedy (including legume cover crops like clover) fields, so proper weed control is important. Nymphs feed for five to eight weeks before entering the adult stage. Newly emerged adults (called froghoppers) are bright green and darken over time to a dull brown. They are very active and readily jump when disturbed. Adults are present on foliage May through November but do not produce any spittle. Adults lay white to cream-colored eggs in the stems and leaves of plants from July through October. These eggs will overwinter and hatch next spring. There is one generation per year in Maryland.
Treatment is rarely necessary for spittlebugs, but u-pick growers need to keep populations to one spittle mass per square foot through prebloom to placate customers. It will be necessary to spread plants and inspect the crowns as well as leaves and stems. Control is considered at one spittlebug per square foot for u-pick operations and 5-6 per square foot (a high population) for everyone else. Aphid control products such as Assail, Thionex, Nuprid, etc. will control spittlebugs too.
Figure 1. Spittle on stems of plants produced by spittle bugs