The froghopper is a small, stout-bodied insect, not an amphibian, despite its name. Measuring less than an inch long, these insects have a frog-like appearance due to their shape and powerful legs. They belong to the Cercopidae family and are found worldwide in various environments. Adult froghoppers are often brown or mottled, which helps them blend in with their plant-based surroundings.
The Signature Foam of the Spittlebug
The most recognizable sign of a froghopper’s presence is the frothy, white foam found on plant stems in spring and summer, commonly known as cuckoo spit or spittle. This foam is not created by the adult insect, but by its immature form, called a nymph, which is also known as a spittlebug. The nymph produces this substance by excreting fluid and then actively forcing air into it through its abdomen, creating a mass of bubbles. This process is similar to how a cappuccino maker froths milk.
The foam serves multiple functions for the nymph’s survival. Primarily, it provides concealment from predators like ants and parasitic wasps. The slippery and bitter nature of the foam makes it difficult for predators to get a grip or a taste. The bubbly mass also acts as a protective barrier, insulating the soft-bodied nymph from temperature fluctuations and preventing it from dehydrating.
Within this self-made bubble house, the nymph remains moist and protected while it feeds and grows. The foam is created from plant sap combined with substances from the nymph’s own glands to increase its viscosity. Positioned head-down on a stem, the nymph allows gravity to help the foam flow over its body, and multiple nymphs may share a single mass of spittle.
Life Cycle From Nymph to Adult
A froghopper’s life begins as an egg laid during the late summer or autumn. The eggs are deposited in the crevices of plant stems or bark where they remain over the winter. These eggs hatch the following spring, and a small, wingless nymph emerges. The appearance of the nymphs coincides with the first calls of the cuckoo, which is how their foam got the name “cuckoo spit”.
This newly hatched nymph immediately begins to produce the protective foam it will live in. The nymphal stage, which is spent entirely inside the spittle, involves several molts as the insect grows larger. After a period of development that can last for weeks, the nymph undergoes its final molt and the winged adult froghopper emerges, leaving the foam behind.
Remarkable Jumping Abilities and Diet
Adult froghoppers are powerful jumpers, a defense mechanism to escape from predators. An adult can leap more than 100 times its own body length, reaching heights of up to 70 centimeters. This feat is equivalent to a human jumping over a 200-meter-tall building. The jump generates a significant force, subjecting the insect to accelerations of over 400 times that of gravity.
This power doesn’t come just from strong muscles, but from an internal catapult-like system. The froghopper uses large muscles in its body to store energy. This energy is then released in less than a millisecond to power the rapid extension of its hind legs.
Both adult froghoppers and their nymphs feed on the sap from plants. They use specialized, piercing mouthparts to tap into a plant’s xylem, the tissue that transports water from the roots. This xylem sap is very dilute and nutrient-poor, consisting mostly of water. Because of this, froghoppers must process enormous quantities of fluid to get the nourishment they need, which is why the nymphs produce so much excess liquid for their foam.
Impact on Plants and Gardens
In most gardens, the presence of froghoppers and their spittle is more of a cosmetic issue than a serious threat to plant health. The feeding of a few insects rarely causes significant damage to healthy, established plants. While heavy infestations can stunt the growth of new shoots or distort leaves, this is not a common occurrence.
The primary concern with froghoppers is their capacity to act as vectors for plant diseases. These insects can transmit the bacterium Xylella fastidiosa from one plant to another as they feed. This pathogen is responsible for serious diseases in a wide range of plants, including Olive Quick Decline Syndrome in Europe and Pierce’s Disease in grapevines.
The bacterium lives in the xylem of plants. When a froghopper feeds on an infected plant, it can pick up the bacteria and carry it in its gut, transmitting it to the next plant it feeds on. The meadow froghopper (Philaenus spumarius) is a common species in Europe and a primary vector of the disease there. While the insect itself is largely harmless, its potential to spread this pathogen is a significant issue for agriculture and horticulture.