They feed on spinach, chard and mustard. They are hard to control because they feed inside the leaves, not on them. Tear off and destroy affected areas. Mustard, collards, and kale will be bothered by cabbage worm. Routine sprayings with Bt when the white cabbage moth is spotted will effectively eliminate them.
Aphids can be a problem if they become too numerous.
They are small and come in all colors. Crops are damaged when the aphids suck the sap from leaves and stems. In bad cases plants will become stunted. Use natural predators, such as Lacewings, Lady Beetles, and wasps. If the predators need help, spray the plants with Ivory snow diluted in water.