What's the white foam on the lavender?

What's the white foam on the lavender?

The question of the day is .... What is the white stuff on the lavender plants?

The white foam is actually known as Cuckoo Spit but it doesn't really have anything to do with cuckoo's other than the fact that it usually starts to appear on plants at about the same time as the cuckoo can begins to be heard each year in May. 

The white foam contains a juvenile froghopper, also known as a spittle bug. The foam protects the larva from predators and also stops it from drying out in the heat.  The larva produces the foam itself. While it is in the foam, feeding safely on the plant, it transforms into its adult form, the froghopper.

The little bug is a sap-sucker but it is generally harmless to plants and should not be considered a pest.