what are these bugs?!

what are these bugs?!

I have a zinnia growing in a pot on my porch that seems to be doing well, only it has acquired a bunch of little bugs on the underside of the leaves. They don't seem to be doing any damage, yet, but I'd like to know what they are and if I need to try and get rid of them before they spread to other plants. I tried a google search and couldn't come up with anything. Thanks for any help available out there! ps: I'm in Boston if that matters.
post harvest question

post harvest question

Mini Water Garden

Mini Water Garden

Garden in September, caterpillar, mystery plant.

Garden in September, caterpillar, mystery plant.

A note on my experience with Ma’dam Wisteria…

A note on my experience with Ma’dam Wisteria…

Bloom time questions

Bloom time questions

old philly apartment

old philly apartment