Bugs can completely mow down a small plant literally overnight. One way to reduce bug damage is to start seedlings indoors, and set them out when they are larger. This works with greens, and many other plants that can be completely gobbled when they are small, but which have greater capacity to withstand insect damage when they are larger. Wait until plants are several inches tall before moving them outside. This won't help with things like bunnies gobbling your greens, because they are big enough to chomp out a dozen plants in a single sitting. But it will slow down the grasshoppers and other munchers.