Insectidal soap spray (not dish soap) -- mix per instructions and cover entire surface of plants, paying particular attention to undersides of leaves. Spray only in morning or late afternoon and when the plants aren't in direct sun.

Do this every three days or so until you have the problem under control, then reduce to once a week.

Best to let the soap spray set on plants for a a couple of minutes then rinse off with water. There is no benefit (residual action) in leaving it on, and it can tend to make your plants more photosensitive.

Also, there are the yellow sticky traps you can use (they are attracted to yellow).