Floating row covers can help.
Grow those plants in a good, healthy soil so the strong, healthy plants that grow up are better able to withstand these pests. Good, healthy plants are lee desirable to pests. Encourage predators to take up residence by planting flowers that produce pollens these predators can live on until the pests show up and do not apply broad spectrum poisons, that will kill off the predators, unless absolutely necessary. Some people report that planting an icycle radish next to the plant helps keep these buggers away. Some people report that a shiny material under the plants (aluminum foil maybe) helps deter them also.