If you are growing cabbage, Brussels sprouts, broccoli, cauliflower, kale, radish, turnip, or rutabaga, you may need to take steps to protect your plants from cabbage worms. These green caterpillars love to chow down on brassicas and similar plants; after they pupate, they emerge as small, cream-coloured moths (that have a couple of dark spots on their wings).
There are many natural ways to control them, such as attracting their predators into your garden. One simple solution is to construct a cover made of tulle (a fabric commonly used to make prom dresses and the like). This fabric mesh allows in rain and sunlight but prevents moths from entering and laying their eggs.
You don’t need to make anything fancy. You can make a wire hoop frame, or simply set up some stakes that you can drape the fabric over so it does not sit on the plants (as I have done above, on my hail-damaged plants). Place something heavy on the edges of the fabric, where they rests on the ground. Or, you can construct something permanent. There are plenty of ideas on the internet.
For more information on cabbage worms, and other methods of controlling them, see https://www.planetnatural.com/pest-problem-solver/garden-pests/cabbageworm-control/.