Cuckoo spit

Actually nothing to do with cuckoos or spit, this froth on the stem of Bird's-foot Trefoil is home for the nymph stage of a Froghopper, the common name for a group of bugs. The ball of froth hides and protects the insect, provides insulation and prevents dessication. Inside it, the nymph feeds on the plant until it is ready to metamorphose into the adult bug which is one of the great athletes of the animal world, able to jump enormous distances for their size and body weight, out-performing fleas.