Officially they are veggies (sap) but I have seen them eating (or sucking on) aphids outside.
The babies are spittlebugs, which suck and bite chunks out of apical meristems.
They suck in the sap and shit it out again while farting. This produces the "spittle"
But as adults they don't do any more damage.
They are the worlds greatest jumpers and they look cool.
More info on froghoppers if you are interested
Here I sit all broken hearted,
Tried to shit but only farted...
Your the only person I know who can go 4th level thinking, and still use the word 'farted' and it sound professional.
How are you today Rico? I see scrogina is nicely nestled in.