CAN YOU PLEASE TELL ME WHAT THIS FOAMY THING IS ATTACHED TO MY DWARF TIBOUCHINA TREE?

Kerrie Stewart, Bayview, NSW

MARTYN ROBINSON SAYS A very interesting insect is the cause of this. When I was a child, we called it ‘cuckoo spit’ and if you carefully wipe away the foam you will find a tiny insect a bit like a tiny cicada nymph (to which it is distantly related). This is a true bug – as it sucks throughout its life – that belongs in the superfamily Cercopoidea, not all members of which produce this foam. The foam protects it and hides it from predators while it is flightless and vulnerable, but once it becomes an adult with wings, it ceases to produce the frothy byproduct of its feeding and lives a normal sap-sucking life. If danger threatens it can spring away and then take flight. While they are sap-sucking insects, they’re generally not a huge problem. I leave them be as I find them interesting to show visitors. Kids love wiping away the foam to find the tiny nymph!