I went into the garden to check on my spiders and found the Golden Penda on the point of blooming. On closer inspection, I found bunches of white bubbles scattered throughout the tree and next to this one, the culprit. This brown insect with the attractively turned-up nose, is a Spittlebug (Philagra parva). Its nymphs produce the spittle in which they hide. The spittle, sometimes called cuckoo spit, is said to reduce the risk of dehydration and to deter predators. They are not good for the tree as they suck on its sap, so I ruthlessly dispersed all the bubbles I could find. I hope this Spittlebug goes elsewhere.