What is causing spit on lavender plants
Cuckoo spit on lavender is caused by a sap-sucking insect, called froghopper. The nymphs of this froghopper produce white foam on the stems and flowers as a protection against predators.
The white foamy spit can also appear on the stems of rosemary and other herbs. The little nymphs suck sap from the plants.
Cuckoo spit on rosemary Rosemary
How do you get rid of cuckoo spit
What can you do, if you have spotted cuckoo spit on your lavender and rosemary shrubs? It is not necessary to remove the plants. The activity of the nymphs causes little harm to the plants.
Use water from a garden hose to wash off the hidden insects and the spit. Alternatively, use gloves and rub the froth off by hand.