Those are aphids on the leaves. They suck juices out of plants. You can mix a drop of dishwashing liquid, a nice splash of alcohol & water in a spray bottle & spray those to kill them without having to use toxic chemicals. Just do it say in the evening so the sun doesn't burn them b/c the soap will tend to make that happen. If it's a day you're going to need to water them then you can spray them & wait 10 minutes & then while you're watering just hose the spray off.
