Froghoppers and cuckoo spit – strange connections

You may have noticed (or maybe when accidentally touched!), small frothy blobs of foam that appear in hedgerows and tall vegetation in May and June. These seemly repulsive cold blobs of spit, hide a delicate baby froghopper inside. Better known as ‘cuckoo spit’ because it appears when the cuckoo bird starts to call in spring, it is in fact the bugs fluid excrement – disgusting but true!

The baby froghopper as it is called, is not a frog at all but an insect nymph.  It taps into the sap of a plant, then eats and exudes the liquid mixed with wax, to produce a frothy mass of bubbles around itself.  The foam protects the developing nymph from drying out and hidden from predators such as ants and parasitic wasps – a clever sap-sucking bubble tactic!

Usually, it’s the cuckoo spit of the common froghopper nymph (Philaenus spumarius) that you see on deciduous trees, bushes, brambles and undisturbed long grass. If you gently wipe some of the froth away, you’ll see the tiny light green or yellow nymph hidden inside.

After a couple weeks the immature nymph finally moults to become an adult and can then fly away. Female froghoppers lay their eggs in plant stems mid-late summer which overwinter as eggs, hatching out the following spring to continue its life cycle.

Interestingly the more robust looking adult froghoppers, who with their armour like wing cases are hard to spot, don’t produce any cuckoo spit. They have large eyes and good vision and can apparently jump up to 70cm high to escape predators or when disturbed. No wonder why they are difficult to observe.

Froghopper nymphs are fun and easy insects to spot with young children which helps to foster a curiosity and a lifelong relationship with the natural world. We all benefit by taking time out to stop and appreciate the magic of little things that often go unnoticed.