Definition of cuckoo spit in US English:

cuckoo spit

noun

  • Whitish froth found in compact masses on leaves and plant stems, exuded by the nymphs of froghoppers.

    • ‘While slugs will ignore it, there may be a small problem with cuckoo spit, or rather the tiny green bug that is encased in the spit.’
    • ‘Developing young create a frothy mass commonly known as cuckoo spit on plants in the early spring and summer to hide from predators such as ants.’
    • ‘Keep an eye out for cuckoo spit, a globule of froth that conceals the tiny froghopper, easily squashed between thumb and finger.’

Pronunciation

cuckoo spit

/ˈkuˌku/