Dave Cheetham (June)
At this time of year you'll come across this everywhere in the hills. These foamy blobs of white liquid are not actually anything to do with cuckoos apart from first appearing at about the same time as cuckoos can be heard.
Instead it is secreted by the immature stages of insects called 'Froghoppers' to protect themselves against predators and to ensure they don't dehydrate during growth.
Once they emerge as adults Froghoppers do not produce any 'cuckoo spit.
But Froghoppers themselves are quite amazing. As adults they can jump from plant to plant with some species able to jump up to 70 cm in the air, a more impressive performance in relation to their body weight than fleas