Rooney, those are stink bug nymphs--very possibly brown marmorated stink bug nymphs.
Thanks JeanW, for that information. Since they were still there I made them into recycling agents for ants by folding the leaf and making a pressure chamber out of it.
Yes, those are BMBW (the M does not stand for mysterious) stage 1 nymphs.
(one key feature being the white bands on the antennae, just visible in your image)
Extreme pest insect. Look around for more. I have only seen two BMBW nymphs here
this year (on blackberry), many days apart.