The Two-lined Spittlebug (Prosapia bicincta) is a small insect recognizable by its dark, almost black body and the two reddish or orange lines crossing its wings. This insect is commonly seen across the eastern United States, often identified not by the adult bug itself, but by the distinctive, frothy white foam it leaves on plants. This foam is the most noticeable sign of the insect’s presence. The answer to this concern is reassuring: the Two-lined Spittlebug is neither poisonous nor venomous to humans or domestic animals.
Are Two-Lined Spittlebugs Toxic to Humans or Pets?
The Two-lined Spittlebug is completely harmless to mammals, including people and pets. It does not possess a stinger or the ability to bite, so it cannot inject venom or other harmful substances. The insect is not venomous because it lacks the specialized apparatus to inject toxins into a host.
It is also non-toxic, meaning it does not contain substances that would cause illness if accidentally ingested. Accidental contact with the insect or its foamy mass is completely safe.
The Purpose and Composition of the “Spittle” Foam
The frothy substance, often called “cuckoo spit” or “frog spit,” is a protective secretion created by the immature nymph stage. The nymph produces this foam immediately after feeding on a host plant, serving as a tiny, mobile shelter for the developing insect.
The spittle mass is formed when the nymph excretes large amounts of excess plant sap, which it must process to obtain the necessary nutrients. The nymph introduces air into this expelled fluid by pumping its abdomen, creating a mass of bubbles. Specialized glandular secretions are added to the mixture to stabilize the bubbles and prevent the foam from collapsing.
This foamy shield provides protection from a range of threats, including predators and parasitoids. The spittle also regulates the nymph’s environment, preventing the soft-bodied insect from drying out. The composition is largely plant sap and excretions, making the foam itself biologically innocuous to the touch.
Identifying and Managing Plant Damage
While the Two-lined Spittlebug is harmless to people, it is considered a pest because of the damage it causes to landscape plants, particularly turfgrass. The insect feeds by using piercing-sucking mouthparts to extract sap from the plant’s xylem tissue. Adult spittlebugs can also inject toxins into the plant tissue, causing a condition known as “froghopper burn.”
Symptoms of an infestation begin with the appearance of spittle masses on grass blades and plant stems, followed by visible plant distress. In turfgrasses like centipedegrass or Bermudagrass, feeding damage appears as yellowing, wilting, or purple streaking of the grass blades, which may eventually turn brown and die. The damage is often patchy and can be mistaken for drought stress or a nutrient deficiency.
For small infestations, a strong jet of water from a garden hose can physically dislodge the nymphs and wash away the protective foam. In cases of severe damage, removing excessive thatch can help reduce favorable egg-laying sites. Chemical treatment with an appropriate insecticide may be necessary, but this should be applied according to label instructions and only after the infestation is confirmed.