An Athlete, Engineering Genius, Living in Frog Spit!

Have you ever wondered what that strange white foam is that appears on your plants in spring and summer? Those little white, wet clumps that magically appear in the armpits of branches or on the stems of your roses, fruit trees, and even your vegetables? If you’re like most gardeners, you’ve probably thought it was a fungal disease, mold, or maybe even soap residue left behind by kids blowing bubbles.

Well, don’t worry: it’s nothing like that. This mysterious foam has some really charming names depending on where you are: “cuckoo spit,” “snake spit,” or even “frog spit”. These picturesque names actually conceal the work of a little survival genius: the froghopper (or spittlebug), a little-known insect that deserves our attention as gardeners.

Far from being a plant disease or even real frog spit, this foam is the result of sophisticated biological technology that would make our best engineers green with envy. Bonus point: it’s (almost) never a problem for gardeners!

Meet the Froghopper, the Leafhopper, or the Spittlebug

Our stars are small insects from the Cercopoidea superfamily. They are small, have several names, and represent approximately 3,000 species of insects worldwide. You can understand why there are so many names! Some are found in North America as well as in Europe and therefore have two names. For the purposes of this article, I am using the word froghopper to refer to all members of the Cercopoidea superfamily.

If any purists happen to be reading this and know of a froghopper that does not produce foam or does not fit my description, and would like to quibble about my generalization…fine.

Adults are generally between 5 and 8 mm (1/4 inch) long—barely larger than a grain of rice. Their sturdy, oval bodies resemble tiny cicadas, and their colors vary greatly depending on the species, ranging from subtle brown to bright black punctuated with vivid red for the most flamboyant ones.

Meadow Froghopper

The most common species in our gardens is the meadow froghopper (Philaenus spumarius), also known as the meadow spittlebug. Since I love teaching you Latin, you should know that spumarius comes from the Latin word spuma, which means… foam!

What makes these little creatures so extraordinary is their athletic performance. Hold on to your hats: some adult froghoppers can jump up to 70 centimeters (28 inches) high! To give you an idea, that’s about 117 times their body size—it’s like you, as a human, jumping over a 66-story building!
These little athletes develop impressive power for their size.

For comparison: fleas, despite being known for their impressive jumps, can only jump 100 times their body size. Froghoppers are truly jumping champions! When they sense danger, they crouch down like a frog (hence their name) and POOF! They disappear into the air faster than you can say “cuckoo.”Un calendrier bien précis

The life cycle of spittlebugs follows a very specific schedule. Adults lay their eggs in the fall in plant stems or under bark. These eggs spend the winter in a warm place and hatch in the spring, usually in April or May. The larvae can produce their protective foam until summer or even early fall. These larvae, which are a pretty lime green color, develop for 1 to 3 months depending on the temperature before becoming adults themselves.

The Famous Foam (Which I Find a Little Disgusting…)

Okay, I’ve raved about this insect and its amazing abilities, but now I have to admit something: even as a nature lover who marvels at these little creatures, I sometimes jump when I brush against a plant covered in this foam and suddenly find myself covered in this slimy substance. I can’t help it, it disgusts me in the moment! There, I said it. You have the right to find it gross, too.
But let’s stay in wonder for just a little while longer, okay? Because it’s really fascinating, I promise!

So how do our little leafhoppers make this foam? The larva, hanging upside down on the plant (a position that allows it to better control foam production), pierces the stem with its mouthparts to suck out the sap. As this sap is very diluted and low in nutrients, it has to ingest huge quantities to extract what it needs.
The excess—mostly water—is expelled through the anus.

But here’s where it gets really cool: instead of just peeing like everyone else, the larva has specialized glands in its abdomen that secrete special proteins. It mixes these proteins with the liquid to be expelled, then pulses air into it using a special valve located on its abdomen. The result? Perfectly calibrated bubbles that form a stable and long-lasting foam. Much more durable than soap bubbles blown by children, anyway!

What Exactly Is This Foamy Mass For?

It’s simply the coziest home imaginable. First, the foam protects the larva from predators—most birds and insects don’t like the taste of this substance. Second, it prevents it from drying out: larvae have soft bodies that quickly lose water, but this water protection acts as a moisturizer. Finally, the air bubbles act as a thermal regulator to keep the temperature stable under the foam, even when it’s hot or cold outside. Jealous? Wait for the best part: since it’s directly on the plant, the insect can sting and drink without leaving its cozy nest. I told you I was grossed out by brushing against this insect pee foam with a larva in it, but it still sounds like a pretty good life!

The composition of this natural foam is surprisingly similar to our modern materials: water, proteins for structure, palmitic and stearic acids (found in soap!), and sugars. With reference to bionics—the science that draws inspiration from living organisms to create technological innovations—we could say that our cercopes invented bubble wrap long before we did!

It’s a real high-tech cocoon and, unlike our plastic packaging, this foam is 100% biodegradable and doesn’t pollute at all. I’m just throwing the idea out there, but if anyone is looking for an eco-engineering research project, there’s something here that could be developed to replace our famous bubble wrap!

Gardening: Friend or Foe?

So, what’s the verdict for our gardens? Well, as is often the case in biology, the answer is nuanced. Froghoppers are what are known as “minor pests with moderate impact” – a category I really like because it reflects reality: neither beneficial nor truly harmful, they are part of the ecosystem and we have to learn to live with them!

The “not so good”: yes, they sting your plants to drink their sap. If you have a large infestation on a young or fragile plant, it can slow its growth or cause slight deformities in the leaves and stems. The sting holes can also serve as entry points for pathogenic bacteria or fungi.

But on the “not so bad” side, leafhoppers are usually few in number and don’t form invasive colonies like aphids. One or two larvae per plant is the norm, and most plants can handle that without any problems. Plus, unlike aphids, which transmit viruses, leafhoppers don’t carry any serious diseases in our region.

The Criterion for Deciding Whether or Not To Intervene

Simple: if you only have a few patches of moss scattered here and there, leave them alone! Your plants are not in danger, and you are providing shelter and food for some fascinating creatures. However, if you see a particularly weak plant covered with dozens of mossy patches, it is best to take action.

How do you get rid of them if necessary? It’s child’s play: just spray them with water! The foam dissolves instantly and the larvae that are dislodged have little chance of survival away from their protection. (Let’s be clear: a JET of water! The larvae must not remain on your plant, or they will make a new foam. We want to BLOW them away!) No need for insecticides, insecticidal soap, or any other chemical arsenal: water, period.

Some gardeners report that spraying the leaves with diluted tomato manure seems to discourage adults from laying eggs, but honestly? If you don’t have a massive infestation, the simplest solution is still to coexist peacefully with these little engineers.

Wonder in the Garden

The next time you come across this white foam in a doorway, resist the urge to wipe it away immediately! Instead, take a moment to observe this marvel of biotechnology hidden at your feet.

This seemingly mundane substance hides a larva that has solved engineering challenges that our scientists are still studying: how to create an insulating, lightweight, durable, and fully biodegradable material from organic waste; how to finely regulate temperature and humidity with such simple means; and how to continuously build a customized habitat that adapts to the needs of its occupant. Our froghoppers are born innovators and have been practicing circular economy for millions of years: they transform “excess” sap into functional habitats, without waste or pollution.

And then there’s the poetic dimension that I love: these discreet little creatures are part of the great orchestra of spring. While the cuckoos sing and the toads croak, they silently build their foam castles, adding their own special note to the symphony of nature’s awakening. (Although later, in summer, I find it disgusting when I get them all over my calves while walking around bare-legged in my backyard!)

So, yes, my kiwi plants sometimes have a few drops of “frog spit” on them, and no, it doesn’t bother me anymore! On the contrary: it’s a sign that my garden is teeming with life, that the ecosystem is working, and that little engineering geniuses have chosen my patch of greenery to set up their summer quarters.