A common sight in gardens, particularly during spring and early summer, is a peculiar white, frothy substance clinging to plant stems and leaves. This foamy mass often resembles a dollop of spit, leading many to wonder about its origin. This intriguing garden phenomenon is the work of a small insect known as a spittlebug, and understanding its habits can shed light on why it makes its bubbly home on your plants.
Identifying the Spittlebug
Spittlebugs are the immature forms, or nymphs, of insects called froghoppers, which belong to the superfamily Cercopoidea. There are approximately 2,500 spittlebug species worldwide, with about 60 found in North America. The most commonly encountered species in many home gardens is the meadow spittlebug (Philaenus spumarius).
The nymphs, found within the frothy masses, are soft-bodied and can range in color from pale yellow, green, or orange. They are small, up to 1/4 inch long, and have noticeable red eyes. As they mature, they undergo several molts, eventually transforming into adult froghoppers. Adult spittlebugs are small, winged insects, 1/4 to 1/2 inch long, and are mottled brown, gray, or black, though some species exhibit distinctive patterns like red or orange stripes. They are known for their ability to jump considerable distances, similar to leafhoppers, but are stouter in appearance.
The Purpose of the Spittle
The distinctive foamy “spit” is produced by the spittlebug nymph and serves several functions for its survival. The nymph creates this froth by consuming large quantities of plant sap. Since xylem fluid is diluted and less nutrient-rich than other plant fluids, the nymph must process a significant volume to obtain sufficient nutrients.
The excess fluid is then expelled from the nymph’s anus and mixed with a sticky glandular secretion. The nymph pumps air into this mixture by contracting its abdomen, creating numerous bubbles that form the characteristic foam. This frothy mass acts as a protective shield, hiding the soft-bodied nymph from predators such as birds, beetles, and parasitic wasps. The spittle also insulates the nymph from temperature extremes and maintains a humid environment, preventing desiccation.
Impact on Plants
While the presence of spittle on plants can be visually unappealing, spittlebugs cause minimal damage to most garden plants. Both the nymphs and adults feed by piercing plant tissues with their needle-like mouthparts and sucking out sap. This feeding can lead to symptoms such as stunted growth, distorted leaves, or slight wilting.
Significant damage is rare in home garden settings. However, in large infestations or on certain agricultural crops, their feeding can reduce yield or weaken plants, making them more susceptible to other stressors. The nuisance is primarily cosmetic, stemming from the frothy masses themselves rather than widespread harm to the plant’s health.
Managing Spittlebugs
For most home gardeners, managing spittlebugs is not necessary due to the limited damage they cause. If the spittle becomes too bothersome or numbers are high, simple, non-chemical methods are effective. A strong stream of water from a garden hose can dislodge the spittle and the nymphs, exposing them to predators or causing them to dry out. This method can be repeated as needed.
Alternatively, the spittle masses can be wiped off plants by hand. If nymphs are present after wiping away the foam, they can be removed and crushed or dropped into soapy water. Good garden hygiene can also help reduce populations the following spring. Pesticides are not recommended or effective against spittlebugs, as the foam provides a protective barrier against sprays.