Answer: Cutworms curl themselves around the stems of little seedlings and essentially chew right through the stems. Styrofoam cups will keep them from accessing the stems. Another way to deal with cutworms is to cut an empty papertowel cardboard tube into 2-3" long pieces and set a piece of the tube around each seedling when you plant them, burying the tube an inch into the soil. Or, push two little twigs into the soil on opposite sides of the seedling, next to the stem. This will keep the cutworms from encircling the stems and killing the plants. White butterflies are probably cabbage moths and they like to lay eggs on broccoli, cabbage and cauliflower plants. The eggs hatch into little green caterpillars which feed on plants.
Zucchini is usually a prolific producer. Plants first produce male flowers and then female flowers. Male flowers have straight stems; female flowers have swellings at the base of the flower just where it meets the stem. Male flowers will not produce squash but female flowers will, if they are pollinated by insects (or in your case, gardeners). If you resist using insecticides in your garden you should have lots of pollinating insects to do the job.
Best wishes with your garden!
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