Spittlebug
The blobs of white froth that appear in leaf joints and stem forks from late May, each containing one small pale sap-feeding nymph. It is one of the most reported and least harmful things in a British garden: on an established plant it does no measurable damage at all, and the correct answer is very nearly always to leave it.
Caused by: Philaenus spumarius · also called cuckoo spit, froghopper
What brings it on
Nymphs hatch in spring and whip sap into froth as a shelter against drying out and predators. Numbers vary from year to year with nothing the gardener does.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Froghoppers and cuckoo spit
Checked 2026-08-13
Usually seen: May, June, July
Preventing it
Ordered by how much difference each measure actually makes, not by how often it is repeated.
- None needed. Nothing about how the plant is grown changes whether spittlebugs arrive.
source
Horticultural consensusmoderate confidence
- Royal Horticultural Society: Froghoppers and cuckoo spit
Checked 2026-08-13
Dealing with it once it is there
- Leave it, or wash it off with a hose if the appearance bothers you. There is no case for an insecticide against an insect that causes no damage.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Froghoppers and cuckoo spit
Checked 2026-08-13
- Cuckoo spit is worth reporting to the Xylella surveillance schemes that ask for sightings, because the spittlebug is a potential vector of a bacterium not currently present in the UK. That is a biosecurity interest in the insect, and it is not a reason to treat the plant in front of you.
source
GrowingHQ editorial positionmoderate confidence
Distinguishes a surveillance interest from a garden action, because conflating the two would turn a harmless sign into an alarming one.
- GrowingHQ editorial synthesis — GrowingHQ
Checked 2026-08-13
What it affects
On sprays and treatments
GrowingHQ does not tell anyone what to apply, at what rate, or how often. Pesticide approvals differ by country, change without notice, and the product label is legally binding — it is also the document you are holding. What is described here is cultural and physical control, which is what a home grower can act on without a label in front of them.