Spittlebugs: Get Rid of Them—or Let Them Be?

Eww—what’s that foamy glop on your strawberry leaf or dahlia stem? It looks like spit, and you probably don’t even want to touch it. Don’t worry—your neighbor’s kid isn’t chewing tobacco in your garden. You’ve got spittlebugs. Here’s how to identify spittlebugs, understand what that frothy foam is, and know when (or if) you should get rid of them.

What Are Spittlebugs?

Spittlebugs are small, winged insects—over 30 species are native to North America. In most gardens, they’re not considered serious pests (aside from those nasty-looking spit globs). However, one species, the two-lined spittlebug (Prosapia bicincta), can damage turfgrass in the eastern half of the United States, ranging from Florida to Maine and as far west as Texas. Nymphs are particularly active in heavy thatch.

While spittlebugs typically don’t appear in large numbers, they can feed on a wide range of plants, including strawberries, herbs, ornamental grasses, perennials, and even trees. Some species are picky; others, not so much. Unlike many garden pests, both the adult and immature stages (called nymphs) feed on plants using their piercing-sucking mouthparts.

The most common species you’ll run into in gardens is the meadow spittlebug, Philaenus spumarius. If you spot one while walking with friends, you might shake your fist at the sky and declare, “Ahhh, Philaenus spumarius, my old foe!” Your friends will think you’re cool and wildly knowledgeable. Maybe. If they’re good friends. (Didn’t work that way for me, come to think of it.)

Spittlebugs usually have just one generation per year, overwintering as eggs in the garden’s duff layer. In spring, the eggs hatch and nymphs emerge—hidden inside their foamy spit bubbles. They’ll molt several times before becoming adults.

Are Spittlebugs Harmful to Plants?

In most home gardens, spittlebugs aren’t harmful enough to worry about. While both nymphs and adults feed by sucking sap from plant stems, the damage is usually minimal—especially when their numbers are low. You might notice a little stunted growth or slight wilting on tender plants, but it’s rarely serious.

The biggest nuisance is the frothy spit they produce to hide in—not actual plant damage. However, in large infestations or with certain species like the two-lined spittlebug, feeding can cause more visible damage, especially in warm-season lawns (Centipedegrass, Bermudagrass, Zoysiagrass, St. Augustinegrass). 

Adults are sometimes found feeding on hollies in late summer and early fall. For most gardeners, spittlebugs are more icky than harmful—and control usually isn’t necessary unless they become unusually abundant.

Why the Spit?

Spittlebugs are unique in that they feed not on the phloem layer of the plant but on the xylem tissues. The xylem carries water and is much more diluted in terms of nutrients, so the spittlebugs must filter out a lot of fluid to get the nutrition they seek. All that water must be excreted, which is how they make the wet, foamy mess we know them by. Spittlebug nymphs are hidden quite well inside the bubbly mass and can be hard to see unless you poke around inside it.

Although the foamy substance resembles spit, it comes not from the mouth but from the other end. Check out this page from the University of Wisconsin Extension for more disturbing details on how the spittlebugs make those secretions they leave on your plants.