[koo-koo-spit, koo k-oo-]
  1. Also called frog spit. a frothy secretion found on plants, exuded by the young of certain insects, as the froghoppers, and serving as a protective covering.
  2. an insect that produces this secretion.

Origin of cuckoo-spit

1350–1400; Middle English cokkowespitle cuckoopint; so called from the spitlike secretion found on the plant and thought to be left by the bird Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for cuckoo-spit

Historical Examples of cuckoo-spit