It is called "cuckoo spit" and is secreted by immature forms of insects called frog hoppers. As far as I know it usually does no harm to plants. Occasionally the young insects might feed on plant tips (if that's where the foam appears) so they might be stunted. The best way to get rid of it, if you are concerned, is to spray it away with water.

It is called "cuckoo spit" and covers immature forms of insects called frog hoppers. It does no real harm to plants as far as I know, although if it is on the tips of plants, and the insects feed on them, they may be stunted or misshapen. If you want to get rid of it, just spray it off with water.

Sorry - don't know why you have two versions of this! :-{

They are actually plants suckers so in large numbers they can cause problems, but one is not going to harm a plant.

It is easy to wipe off with your fingers or give a quick blast from the hose.

Thanks for your quick response, I will hose off as they are popping up on all 8 lavender seal plants and I noticed some on my highland dream daisies today.

I'm so glad you asked this question.
I have the same frothy spit on my Lavender. I'll rush out and blast it off
Thnks everyone.