Thank you for the excellent images. They clearly show that the small black things are aphids, common soft-bodied insect pests which are easy to manage. You can squish them, wash then off with a harsh water spray, or spritz them with insecticidal soap, diluted according to directions. Whatever your choice, repeat as needed, perhaps every several days.

The first image clearly reveals that If you enlarge a bit.  You can also see a small parasitoid wasp at the lower left; it doesn’t sting people or pets but does help limit the number of aphids.  Other things to recognize in that same image are some small white flecks with dark extensions; they’re the exoskeletons (skins) that the aphids shed before they were able to become the next larger and older stage. Also notice a few of the black aphids have wings; this indicates that the population is becoming crowded. See “Aphids” at http://ipm.ucanr.edu/PMG/PESTNOTES/pn7404.html.