Cheryl Moorehead, Bugwood.org
These sometimes appear on the stems and leaves of strawberries at about the time of bloom. The insects are known as spittlebugs because of the peculiar, spittle-like substance with which they cover themselves. They often are seen in meadows and on plants in uncultivated fields.
Spittlebugs have sharp beaks with which they pierce the stems of plants and suck the plant juices. The insects first feed at the base of the plants but later move up to the more tender foliage. The nymph or young stage produces the frothy material and remains in this protective substance until developing into the adult stage. The insect overwinters as an egg. Nymphs appear in May or June and complete their development in 5 to 8 weeks. Egg laying occurs primarily during September and October. Eggs are inserted into the lower parts of the strawberry plant. Only one generation appears each year.
Feeding activities of large numbers of these insects cause plants to become stunted, and berries do not attain full size; however, the greatest impact of this insect is the spittle masses on the plants, which are very annoying to strawberry pickers. Weedy fields are more heavily attacked.
Control might be indicated if nymphs (without frothy masses) are present when the first blossom clusters separate. Spittlebug populations infrequently need pesticide treatment and should be treated only when there are more than a few per square feet.