What Are Spittlebugs?

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Updated on January 13, 2020

The first time you encountered spittlebugs, you probably didn't realize you were looking at bugs. If you've ever wondered what rude person came along and spit on all of your plants, you've got spittlebugs in your garden. Spittlebugs hide inside a frothy mass that looks convincingly like spit.

What Are Spittlebugs?

Spittlebug secretion — Sanjay Acharya / Wikimedia Commons/ CC BY-SA 4.0

Spittlebugs are actually the nymphs of true bugs known as froghoppers, which belong to the family Cercopidae. Froghoppers, as you might guess from their name, hop. Some froghoppers bear a passing resemblance to tiny frogs. They also look similar to their close cousins, the leafhoppers. Adult froghoppers don't produce spittle.

Froghopper nymphs—spittlebugs—feed on plant fluids, but not on sap. Spittlebugs drink fluids from the plant's xylem, the vessels that conduct water from the roots to the rest of the plant's structures. This is no easy task and requires extraordinarily strong pumping muscles since the spittlebug is working against gravity to pull liquid upward from the roots.

Xylem fluids aren't exactly superfoods, either. The spittlebug has to drink enormous volumes of the fluids to derive enough nutrition to live. A spittlebug can pump up to 300 times its body weight in xylem fluids in a single hour. And as you might imagine, drinking all that fluid means the spittlebug produces a lot of waste.

How Are Spittlebug Secretions Produced?

If you're going to excrete massive amounts of waste, you might as well put it to good use, right? Spittlebugs repurpose their waste into a protective shelter, keeping them hidden from predators. First, the spittlebug usually rests with its head facing downward. As it voids the excess fluids from its anus, the spittlebug also secretes a sticky substance from abdominal glands. Using caudal appendages, it whips air into the mixture, giving it a foamy appearance. The foam, or spittle, flows down over the spittlebug's body, hiding it from predators and gardeners alike.

If you see spittle masses in your garden, gently run your fingers along the plant stem. You'll almost always find a green or brown spittlebug nymph hiding inside. Sometimes, several spittlebugs will be sheltered together in one large frothy mass. The spittle mass does more than protect the spittlebug from predators. It also provides a high humidity microclimate and shields the bugs from rain. When the spittlebug nymph finally molts into adulthood, it leaves its spittle mass behind.

Sources

Bugs Rule: An Introduction to the World of Insects, by Whitney Cranshaw and Richard Redak
Borror and DeLong's Introduction to the Study of Insects, 7th Edition, by Charles A. Triplehorn and Norman F. Johnson
Bug Guide. Family Cercopidae – Spittlebugs.