Invertebrates
Froghopper
Philaenus spumarius · also called spittlebug, cuckoo-spit insect
The little frothy blobs on plant stems in spring, the ones country lore calls cuckoo spit, are made by a sap-feeding insect hiding inside. As an adult, that same insect can throw itself into the air with a force several hundred times gravity, the most violent launch of any animal.
Overview
Philaenus spumarius, the meadow froghopper, is a small, squat, blunt-headed plant bug, 5 to 7 mm long, that feeds on dilute xylem sap from a huge range of plants. It is one of the most widespread and abundant plant bugs in the world.
The record jump
An adult can accelerate at around 400 times gravity, launching over 70 cm, harder than a flea. The legs cannot move that fast, so the insect slowly loads a spring of rubbery resilin, latches its legs, and releases the whole store in under a millisecond.
Cuckoo spit
The nymph feeds inside a mass of froth it makes from a secretion pumped full of air. The foam keeps it moist, hidden, insulated, and distasteful. It is harmless to plants and people.
A crop threat
Because it feeds on xylem, the froghopper spreads Xylella fastidiosa, a bacterium that blocks a plant’s water vessels and has devastated olive groves in southern Europe.
Status
Not Evaluated and extremely common across Europe, Asia, and North America.
Froghopper: common questions
What is cuckoo spit, and is it dangerous?
Cuckoo spit is the frothy white blob you see on plant stems and leaves in late spring and early summer. It is not spit and has nothing to do with cuckoos; it is a protective foam made by the young froghopper, or spittlebug, which is feeding on sap inside it. The nymph produces a watery secretion and pumps air bubbles through it to build the froth, which keeps its soft body from drying out, hides it from predators and parasites, buffers the temperature, and is distasteful. It is completely harmless to people and pets, and a froghopper nymph on a garden plant causes little or no real damage, so the froth can simply be left or hosed off.
How can such a small insect jump so hard?
It uses a catapult. A froghopper's jumping muscles are large but, like all muscle, they contract too slowly to produce an explosive launch on their own. So the insect contracts them slowly in advance, storing the energy by bending a bow-shaped section of its thorax and compressing internal pads made of resilin, a rubbery protein, while small catches hold the hind legs cocked. When the catches release, the stored energy is dumped into the legs in well under a thousandth of a second, flinging the insect upward at an acceleration of several hundred times gravity. Fleas, click beetles, and trap-jaw ants use versions of the same spring-and-latch trick.
Does the froghopper out-jump the flea?
In terms of the force involved, yes. Measurements published in the 2000s found that the froghopper experiences a peak acceleration of around 400 g during take-off, compared with roughly 100 to 150 g for a jumping flea, so the froghopper undergoes a more violent launch. The flea still wins on jump height relative to body length in some comparisons, and other small animals such as certain planthopper nymphs and springtails also perform astonishing jumps, so the exact ranking depends on what is being measured. But the froghopper is firmly among the hardest-accelerating animals known.
Is the froghopper a pest?
On its own, mostly not. A froghopper nymph or two on a garden plant does negligible harm, and the adults, though they feed on sap, rarely occur in numbers high enough to hurt a healthy plant. The serious concern is disease transmission. The meadow froghopper is the main carrier in Europe of Xylella fastidiosa, a bacterium that clogs a plant's water-conducting vessels and can kill olives, grapes, almonds, and many ornamentals. Since Xylella reached southern Italy around 2013 and devastated olive groves, controlling froghopper populations in and around orchards has become part of managing the outbreak.