The frothy masses of “spit” often seen on plant stems are the tell-tale sign of spittlebugs, also known as froghoppers, which are small insects belonging to the superfamily Cercopoidea. These common garden visitors are primarily a concern for plant health due to their feeding habits. Spittlebugs do not pose a health threat to humans or pets. They are plant feeders that do not bite, sting, or transmit diseases to people.
Do Spittlebugs Bite Humans?
Spittlebugs do not bite humans because their mouthparts are not designed for piercing skin or consuming blood. The insects are equipped with specialized, needle-like mouthparts known as a stylet, which is a modified structure used strictly for plant feeding. This stylet is specifically adapted for penetrating tough plant tissues to access internal fluids, not the soft tissue of a mammal.
They are not aggressive and have no biological reason to interact with humans, as they do not feed on flesh or require blood meals for reproduction. Anecdotal reports of a spittlebug “bite” are generally considered accidental probing or a sharp sensation caused by the insect’s clumsy landing or attempt to hold on. Spittlebugs are entirely harmless to people and pets.
Identifying the Spittle Mass and the Insect
The most distinctive sign of a spittlebug presence is the frothy, white mass that looks like saliva on plant stems and leaves. This foamy shelter is produced by the nymphal stage and is often called “cuckoo spit.” The mass is created when the nymph extracts large amounts of plant sap, excretes the excess fluid, and then mixes it with a stabilizing substance and air bubbles using its abdomen and legs.
The Spittle Mass
The spittle mass serves several protective functions for the vulnerable nymph within. It acts as a defense mechanism against predators and parasitoids, provides insulation from extreme temperatures, and maintains a high-humidity environment to prevent the soft-bodied nymph from drying out.
The Adult Insect
The adult stage, often called a froghopper, is a small, stout insect typically about a quarter-inch long, resembling a stubby leafhopper with enlarged hind legs for jumping. Adults are generally dull-colored, ranging from tan to brown or gray, and are rarely seen due to their size and habit of quickly jumping away when disturbed.
How Spittlebugs Feed on Plants
Spittlebugs are classified as piercing-sucking insects, meaning they feed by inserting their stylet into a plant’s vascular system. Unlike many other plant-sucking insects that target the sugar-rich phloem, spittlebugs exclusively feed on the xylem sap. Xylem sap is the water-conducting tissue that transports water and dissolved nutrients from the roots to the rest of the plant.
Because xylem sap is extremely low in amino acids for growth, the nymph must consume an enormous amount of fluid to gain enough nutrition. A single nymph can process up to 280 times its own body weight in sap within a 24-hour period. This heavy feeding can cause minor damage to host plants, resulting in stunted growth, distorted or curled leaves, and a general weakening of the plant. While the damage is usually minor and cosmetic, severe infestations can occasionally cause more noticeable harm.
Simple Methods for Control
Since spittlebugs are primarily a nuisance rather than a major threat, control methods focus on simple, non-chemical solutions. The most effective approach is manual removal.
Manual Control Methods
- A strong, directed jet of water from a garden hose will wash the insects and the foam off the plant stems, often drowning the nymphs or exposing them to predators.
- Manually wipe the spittle masses off the plants with a damp cloth or paper towel, removing the nymph inside.
- To help prevent future infestations, keep garden areas clean by removing leaf litter and plant debris where the females lay their overwintering eggs.
- Maintaining plant health and avoiding over-fertilization can also make plants less susceptible to high populations.