Beneficial Insects in the Garden
Ahealthy garden abounds with insect life–and, as gardeners, it's helpful to know which insects are working with us rather than against us. It can be frustrating to spend time and money on plantings only to watch them be devoured by pests like flea beetles, tomato hornworms, and aphids. Rather than resorting to pesticides, though, the first line of defense should be getting out to the garden regularly to monitor plants for damage and to learn to distinguish between friend and foe. Handpick eggs, larvae, and adults of pests whenever possible and keep your plants well-fed and watered (so that they can mount their own natural defense). Use row cover to protect crops from cabbage worm, cabbage looper, flea beetles, onion maggots, thrips, and early season cucumber beetles. However, the most effective pest-prevention strategy of all may be to grow a wide variety of plants that support beneficial insects.
Beneficial insects include pollinators (such as bees, flies, butterflies, and moths), predators (like lacewings, preying mantids, and ladybugs), and parasitizers (brachonid wasps and tachinid flies). Parasitic wasps are very tiny and generally don't sting people. Preying mantids and dragonflies are somewhat indiscriminate in their appetite but can help get pest populations down. Spiders are beneficial predators too, although these are arachnids rather than insects.
Growing a diversity of flowers and herbs creates the necessary habitat for beneficial insects to complete their lifecycle and go to work for you. When allowed to flower, even mustard plants will support beneficial wasps, flies, and beetles. Learn to identify the insects in your garden at every stage of their development: many beneficial insects are most effective in their larval stage, such as aphid lions (lacewing and ladybug larvae). Here are just a few of the many beneficial insects that you can find in a healthy garden: