After sojourning for a time in the cuckoo-spit, the frog-hopper becomes a winged insect.
"The Outline of Science, Vol. 1 (of 4)" by J. Arthur Thomson
Cuckoo spit: liquid in the form of bubbles produced by members of the family Cercopidae and which often conceals the producer.
"Explanation of Terms Used in Entomology" by John. B. Smith