Above: Froth on a tansy plant in Bonnefont garden on a May morning. In the Middle Ages, this foamy substance was believed to be the spittle of the cuckoo. The froth is secreted by insects known as spittle bugs.
The cuckoo-spittle, gowk’s-spittle, cuckoo’s-spittens, frog-spit, toad-spit, snake’s-spit, or wood-sear, of England and Scotland; Kukuk-speichel, and hexenspiechel (witch’s spit) of the Germans; gugger-speu of the Swiss; gred-spott (frog-spit) of the Swedes; giogespit of the Danes; trold-kiaringspye of the Norwegians; and crachat de coucou of the French . . .
—James Hardy, “Popular History of the Cuckoo.” In The Folk-lore record, Vol. 2. London: Nichols & Sons, 1879.
When walking through a meadow or a garden on a spring morning, you may have noticed a white froth on the leaves of some plants. In European folklore, this froth is known as cuckoo spittle, since it coincides with the return of the migrant cuckoo, Cuculus canorus. (For more information on cuckoo lore in the Middle Ages, see my post “Summer is Icumen In” (April 4, 2009).
Although welcomed as a herald of spring, the cuckoo also had sinister associations with snakes, illicit sexuality, and death, as did many of the plants that bloomed during the months of April and May, a time when witches and fairies were believed to be abroad and active. The names of many of the so-called cuckoo flowers that bloom when the bird is heard bear out these ominous connections. (For more information on cuckoo flowers, see the post “Adam and Eve and Arum” (May 22, 2009).
Saliva, like other body fluids, was important in ancient and medieval spells and charms, and the “spittle” was sinister in and of itself. The connection made with the cuckoo darkened the interpretation of this mysterious froth, which appeared overnight. The acrid taste of the froth was taken as further indication of its noxious character, and it was thought that cattle grazing on plants covered with cuckoo spittle would sicken and die. (The hexing of cattle was one of the chief mischiefs perpetrated by witches and fairies.)
The froth is actually secreted by insects known as spittle bugs or froghoppers. The foam conceals the vulnerable larvae, or nymphs, of these species from predators; it also protects against extremes of heat and cold, as well as dehydration. The nymphs pierce the plants and suck the sap. The excess fluid excreted in the process creates the protective foam, which has a bitter taste that is a further defense against predators. Although some species are serious agricultural pests, most froghoppers do not cause significant damage to the host plant, beyond some distortion or damage to the tender growing tips. The foam can easily be washed away with water or brushed away by hand.