If you’ve spent much time outdoors exploring the woods and the fields at this time of year then you’ve probably come across this foamy substance.

Cuckoo spit - Chris Calow

Have you ever actually taken the time to stop and examine it, or wondered what it is and what produces it? I did and the answer is fascinating.

It is often known as cuckoo spit, a rather misleading name as it is not produced by cuckoos and it certainly isn’t their spit. The name originates from the similar dates at which both cuckoos and the foamy substance start to be seen in the British countryside.

The foam is actually created by an insect called a froghopper. The larvae of froghoppers use the foam as a form of defence against predators such as birds. The larvae can hide inside the foam, which tastes foul just in case they are discovered hiding under the foam by something which would like to eat them.

Masses of cuckoo spit - Chris Calow

The larvae create the foam by excreting the plant sap which they feed on and mixing it with air bubbles. If you’re a gardener and you have froghoppers in your garden there is no need to worry, they don’t actually harm the plants which they feed on.

Adult froghoppers feed on sap too but they don’t need to create the foam to defend themselves, they have a remarkable trick of their own. Before I tell you what it is why not have a guess. The clue is in the name. That’s right they jump. In fact some species can jump vertically more than 70cms! Relative to size and weight that’s a more impressive performance than a flea.

Red and black froghopper - Chris Calow

Next time you see a little bit of cuckoo spit why not take a minute to admire it, or better yet, carefully scrape away the foam and have a peek at the animal that dwells within. Just make sure you put them back somewhere safe so they can create another foamy little home.

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