How to recognise it
The adults are 4 to 6mm long with prominent eyes and powerful back legs which enable them to jump when disturbed. The nymphs are pale yellow/green coloured and usually covered in a distinctive white froth known as ‘cuckoo spit’.
Female adults lay batches of around 30 eggs in the stems of plants in autumn before dying. The eggs overwinter, hatching in May. The nymphs then start to feed, producing frothy ‘cuckoo spit’ liquid from their anus which is thought to protect them from desiccation and from predators. They mature into adults by late July.
Why it’s a problem
The nymphs feed on the stems, leaves and roots of plants, leaving behind white frothy ‘cuckoo spit’. Generally they cause little damage but growth may be distorted if they feed on the tip of a shoot. The adults feed on sap but rarely cause noticeable damage.
Where you are likely to find it
The nymphs feed from May to July, and continue to feed on sap as adults until the autumn. A wide variety of garden plants can be targetted, but apples, blackberries, pears, raspberries, strawberries, perennial asters, campanulas, chrysanthemums, coreopsis, dahlias, fuchsias, geums, lavenders, lychnis, phlox, roses, rosemary, rudbeckias, solidagos and willows seem particularly susceptible. Generally the infestations occur outdoors but greenhouse plants can also be affected.
How to deter it
Hard pruning in winter or early spring would remove overwintering eggs, but froghoppers cause so little damage that this action is rarely necessary.
How to get rid of it
Usually a strong blast of water from a hosepipe or pressure washer is enough to dislodge nymphs and their froth, or you can simply wipe them off by hand. A systemic insecticide could be used instead.
Is it good for anything?!
Other useful information
Various species cause cuckoo spit, including the ‘red and black froghopper’ (Cercopis vulnerata), but the most common in northern Europe is the ‘common froghopper’ (Philaenus spumarius).
“Cuckoo spit”, the common name for the froth excreted by froghopper nymphs, derives from its appearance in late spring at a time when cuckoos are first heard. It has no other link to the bird.