The name cuckoo-spit is said to have derived from the arrival of the spittle on plants which coincided with the first call of the cuckoo in Spring. There are also oblique references to superstitions about spitting whenever a cuckoo is heard to avoid bad luck. Certainly cuckoo spit was an important ingredient in witches brew1 and in Scandinavian countries the froth is known as ‘witches spit’.
What is Cuckoo Spit?
Cuckoo-spit is the white frothy substance found on certain plants during the Spring and early Summer. It is produced by the Froghopper, or Cuckoo-Spit insect which is sometimes called the Spittle-bug.The froth is also known in the United States as ‘snake-spit’, ‘frog-spit’ or ‘toad spit’.
What is a Froghopper?
The Froghopper is an insect. A member of the order Homoptera. As such it is related to both cicadas and aphids. The Common Froghopper2 is the most widespread example in the UK although related species are found world-wide. Typically the adult froghopper is between 4 and 7mms long. They are called froghoppers because from above they appear froglike and they are able to hop significant distances when disturbed.
Habitat
In nature the habitats they are most often found in are woodland edges and grassland. However, they are also a pest known particularly to fruit-growers. They feed on plant sap which they extract from the leaves and stems of plants. This causes minor damage in itself but the insects carry viruses which can cause serious harm to crops. The eggs are laid on the a wide variety of plants including nettles and grasses as well as the tender young shoots of willow, cherry and apple. In gardens they are frequently encountered on such plants as chrysanthemum, dahlia, fuchsia, lavender, rosemary and rose.
Life-cycle
The lifecycle of the Froghopper is in three stages;- egg; nymph and adult. In this respect it is similar to such insects as grasshoppers and dragonflies.3.
Up to 100 eggs are laid by the adult females in the late summer into an incision made into the tissues of the host plant. The eggs hatch into nymphs in the following Spring.
The nymph is the sexually immature stage. It resembles the adult in shape but unlike the adult has no wings and only rudimentary legs and eyes. Crucially it has but a thin outer body layer or exoskeleton which unlike the adult is not covered by a waxy layer. For this reason it needs to protect itself from desiccation. This is achieved by surrounding itself in a frothy mass of soapy bubbles known colloquially as Cuckoo-Spit. The froth also helps to protect the developing nymph from predators by disguising the nymph. If determined to seek out the insect the predator it will be dissuaded by the unpalatable taste of the froth. (If you do not believe that, try it sometime for yourself!) Enclosed within this froth the nymph moults several times before emerging as the adult in early summer.
The adult has a hardened exoskeleton enabling it to survive without need of protection of the cuckoo-spit. They are normally a mottled red green or brown in colour although there is wide variation in hue. The adult has well developed legs which enable it to ‘hop’ very large distances to avoid predation. They also have a single pair of wings4. After laying its eggs the adult female dies.
How is Cuckoo-spit produced by the froghopper?
The nymph feeds head downwards with its syringe-like mouthparts embedded in the tissue of the plant. The froth is created by the insect excreting a fluid, the result of excess undigested plant sap, exuding through the anus that is mixed with a secretion from the abdominal glands. Air bubbles are introduced through a special valve on the abdomen which acts like a bellows and the contact with the air causes the liquid to ferment forming the froth (or spittle).
1 Macbeth
2 Philaenus spumarius
3 This lifecycle distinguishes it from that of such insects as butterflies and bees which have four distinct stages; egg, larvae, pupa and adult and go through a metamorphosis at the pupa stage
4 the second pair of wings are modified to protect the true wings
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