Several developmental stages of aphids, larger parasitized aphids (called aphid mummies), and the white cast-off exoskeletons of the growing aphids.

suggestions to treat

Spray with water.

tj

Hand spray with a solution of insecticidal soap to kill the aphids - but inspect for beneficial insects & their larvae first. Those could include ladybugs, lacewings, and syrphid flies (hover flies). If present, they are a natural solution, and will control the aphids on their own if given time. Killing them benefits the aphids, which will replenish their population more rapidly than the predators.

Insect predators usually control aphid populations in my gardens. The only time I would spray is if the aphids - and their ant herders (see below) are spreading disease from plant to plant.

I don't see any ants in the photos; but if they are present, they could be "farming" the aphids & will re-infest the plants. Normally the ants are just a minor nuisance, but if damage becomes severe, boric acid baits will control the ants.

Aphids have such soft bodies that a sharp spray of water kills them. Any washed off and not killed are unlikely to find their way back to the plant. Keep an eye out for any you may have missed and repeat as needed.

tj