This cold Alder Spittlebug, Aphrophora alni, sat on a rose leaf, cold and reluctant to fly, so I decided to give it a session on the white bowl, and it graciously obliged. The Alder Spittlebug is one of the largest British froghoppers (9-10 mm), so called for their - alleged - resemblance to a frog and their ability to jump. Unlike the Common Froghopper, which is smaller and on close inspection covered on fine hairs, the Alder Spittlebug has fine dark punctures and is less variable in colour. They also have a distinctive keel in the middle of the thorax, visible in the photo below. They are sap feeding insects, both nymphs and adults, and they feed on a range of plants. Adults are usually found in trees, but they descend to lower vegetation to lay eggs. 
 Froghoppers are the fastest jumping insects, outperforming fleas: they can jump up to 70 cm in the air, with an acceleration equivalent to 550 times gravity. Their hind legs - tucked underneath their wings in the photos - are powered by huge muscles in the thorax and the catapult-like jump is effected by elastic energy stored in a membrane. Another fascinating aspect of their behaviour is sound communication. Froghoppers and other small homoptera have a repertoire of vibrational drumming sounds - inaudible for us - which transmit through the substrate where they sit and that individuals use in communication. Songs can be territorial, regulating the distance between feeding individuals, or involved in attracting a mate, emitted by males and to which females respond, and they also sing as a form of fighting when two males are close together or when in distress.
More information
Burrows M (2009). Jumping performance of planthoppers (Hemiptera, Issidae). The Journal of experimental biology, 212 (17), 2844-55 PMID: 19684220 Tishechkin (2003). 

Tishechkin, D.Y. (2003). Vibrational communication in Cercopoidea and Fulgoroidea (Homoptera: Cicadina) with notes on classification of higher taxa Russian Entomology, 12, 129-181

The lavender bushes are still far from bloom, but they are covered on the decorative white froth blobs produced by the common froghopper or meadow spittlebug, Philaenus spumarius. The spittle-like foam (widely known as cuckoo spit in the UK) hides green nymphs which suck on the plant sap safe from predators and dessication.
 I uncovered the soft-bodied, green nymphs this morning by gently spraying the spit with water. Three were hiding in a quite large spit, head down, nestled in the joint between leafs and stalks, so that they resemble plant buds. In the afternoon they were covered again in the spit. To make the spit they mix air with their watery deyections and a surfactant secreted by abdominal glands using their legs, and they rest head-down, the spit rapidly covers them.

A review of Philaenus spumarius life history indicated that there is no less than 16 colour forms, and a lot of research has been devoted to the genetic basis of this colour polymorphism.
More information:
Yurtsever, Selcuk (2000). On the Polymorphic Meadow Spittlebug, Philaenus spumarius (L.) (Homoptera: Cercopidae). Turkish Journal of Zoology, 24 (24), 447-459. here.