Gardening Laidback Gardener Tip of the Day Plant pests

Foam on Your Plants? It’s Just Frog Spit!

20170627A MuPaily, WC
This strange bubbly froth is called frog spit. Photo: MuPaily, Wikimedia Commons

No, not real spit from a frog, but the cluster of small transparent bubbles in a whitish foam is instead caused by an insect called a spittlebug or froghopper, in the Cecropidae family (also in the newly created families Aphrophoridae and Clastopteridae), and goes by the name of frog spit, cuckoo spit or snake spit.

A generation ago, most curious children were in contact enough with nature to have examined the spittle and would have discovered on their own that there is a small pale green to yellow insect inside, but nowadays many children don’t venture far from the asphalt and concrete of the city. When they become young adult gardeners (and gardening has never been as fashionable among the younger generation as it is today!), they can be mystified by this weird froth. What is it and what to do about it?

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This spittlebug nymph is feeling quite naked with its bubble shelter removed. Photo: treegrow, Flickr

The insect found in the bubble shelter is the nymph of a spittlebug. Soon its birth, it pierces the stem of its host plant and uses the sap that flows from it to make the bubbles in question, inflating them with air from a special opening on its underside. Not only does this spittle conceal the nymph from predators, it insulates it from sudden temperature changes and prevents it from drying out. Moreover, the foam has an acrid taste, enough to keep even the most stubborn predators at bay.

There are over 850 species of spittlebugs throughout the world. In fact, if there are plants nearby, there are probably spittlebugs! Some are quite ubiquitous and will settle on almost any plant, either woody or herbaceous, but there are species that are exclusive to certain plant groups. In the average garden, you’ll most often see them on small fruits and such ornamental flowers as chrysanthemums, dahlias, mallows, roses, fuchsias and lavenders.

20170627C Charlesjsharp, WB
Adult spittlebug. Photo: Charlesjsharp, Wikimedia Commons

The adult is a small hopping insect, often brown or beige. It is seldom seen, for not only does its color help conceal it, but it leaps to other plants when people approach. When a spittlebug is ready to jump, it crouches down and takes on a froglike posture, whence the name “froghopper.”

The adult spends its summer feeding on the sap of plants. At the end of the season, the female pierces holes in a stem and deposits its eggs. They hatch in the spring and, with the return of favorable temperatures, form a bubble home. The nymphs feed on the plant for several weeks, molt a few times, then emerge as adults. The foam is then washed from the plant by the next hard rain. There is only one generation a year. Given the pest’s life cycle, the appearance of frog spit is often considered a sign of the arrival of summer.


Just add a bit of frog spit to the pot the next time you get the coven together to make a bit of brew! Illus.:

Our ancestors found frog spit a very mysterious product indeed, believing it was produced by frogs, cuckoos, snakes or even witches. In fact, frog spit has been a popular ingredient in witches’ brews over the centuries!

Damage Caused

A single spittlebug nymph causes little immediate damage. However, when there are several bubble shelters on the same plant, the growth and vigor of the plant may be affected and the leaves and stems may be deformed.

The real problem, though, is that spittlebugs can transport viruses from one plant to another and that the holes they pierce can leave an open wound on the plant that will be prone to microbial infestations.

It is, however, the adults who cause the most damage and their great mobility makes control difficult. The effect of a single nymph on a plant is minimal.

What to Do?

What to do when you see frog spit on one of your plants? You can simply ignore it if you want to, as it causes little damage. Or you can remove the nymph with your fingers or wash the spittle off with a strong stream of water, thus exposing the creature to the drying sun. When there is more than one patch of frog spit on the same plant, however, it’s best to remove them, as an accumulation of nymphs could damage the plant’s health.

Frog spit: a disgusting name, but it hides a most interesting little insect!20170627A MuPaily, WC

Garden writer and blogger, author of 65 gardening books, lecturer and communicator, the Laidback Gardener, Larry Hodgson, passed away in October 2022. Known for his great generosity, his thoroughness and his sense of humor, he reached several generations of amateur and professional gardeners over his 40-year career. Thanks to his son, Mathieu Hodgson, and a team of contributors, will continue its mission of demystifying gardening and making it more accessible to all.

1 comment on “Foam on Your Plants? It’s Just Frog Spit!

  1. Thank you for this. I see these all the time and I was wondering what they were. Now I know.

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