Chances are, there are more good insects in the garden at present than bad ones.
Insects are needed to properly pollinate fruits and vegetables, and to burrow through and aerate the soil so plant roots can get sufficient air, water, and fertilizer. Some bugs feed on weed seeds to keep those populations lower than they would be otherwise, while others devour dead plant matter, dung, and compost. Still others act as food sources for birds.
And let’s not forget the backyard rock stars that prey on harmful insects, or the supermodel set of butterflies that add glamor to even the most practical vegetable plot.
Applying a spray or powder broad-spectrum insecticide, such as Sevin, to eliminate bad bugs will indiscriminately take out a lot of the helpful bugs, too. The key is to know which are advantageous, which are destructive, and which, in various stages of their lives, are both.
A prime example of the last category is a butterfly that will eat plant leaves in its caterpillar stage and then pollinate flowers once it becomes a winged beauty. The solution? Planting butterfly plants, such as milkweed, that the caterpillars can feast on so that they leave your crops alone.
Predators and Parasitoids
While the above subtitle might sound like a scary science fiction movie title, predators and parasitoids are actually the good guys.
Of the predators, lady beetles (aka ladybugs) are one of the most famous, but most people don’t know that in addition to their renowned bright red coloring and distinctive black spots, these dome-shaped wonders also come in yellow, orange, pink, and all black.
Be aware that their larva can look a bit daunting. About a half-inch in length on average, their six-legged, alligator-like spiny bodies are black with orange, red, or white markings mid-body.
Similar to ladybug larvae, but without the spines and color, common ground beetles feed on a wide variety of harmful insects. They are most often found under leaves, logs, mulch, and stones.
The praying mantis is another well-known predator, but beware; they’ll eat anything they can catch, including valuable insects such as bees. If there are some naturally in the yard, that’s great, but don’t order an army of them, or they could decimate the good bug population.
Assassin bugs come in various shapes and sizes, with most looking like beetles with long, skinny, spider-like legs. Two common types are the wheel bug and the predatory stink bug. All feature a straw-like mouth appendage to stab their prey and suck the fluids out of them.
Delicate green lacewings in adult form can help pollinate flowers, but it’s at their alligator-looking larval stage that they make meals of destructive aphids and other soft-bodied insects.
Common wasps—including yellow jackets, bald-faced hornets, and paper wasps—will capture and kill a large number of garden pests daily to feed their young. Syrphid flies, which look like wasps and bees with their yellow, orange, and black markings, can also consume a large amount of harmful, small, soft-bodied insects.
A third, unique category of helpful wasps is parasitoid wasps, which lay their eggs on their favorite bugs (which are usually garden villains, such as the dreaded tomato horn worm). Once the eggs hatch, they use the bug as a food source, killing it.
The term parasitoid wasps encompasses a large number of different species, ranging in size from a fleck of pepper to those with bodies up to a half-inch long. They come in colors including black, gray, and brown, as well as various colors and patterns. As they’re so small, they often live and thrive unseen by the gardener. What they lack in stature, they usually make up for in volume.
Being so small, with a diet of plant nectar, they are extremely sensitive to chemical insecticides. That brings up the next topic.
Building a Beneficial Ecosystem
The first step is to nurture the good bugs that are already in the garden. Replace broad-spectrum commercial insecticides with organic insecticidal soap such as Dr. Bonners, horticultural oils such as neem (a tree oil extract), and botanical insecticides such as pyrethrins, which are extracted from chrysanthemums. While they can also kill good bugs, unlike their commercial counterparts, they are broken down relatively quickly by weather and soil microbes after use.Apply them only as needed in the areas needed, preferably in the evening when the pollinators are done. Be careful not to spray the open flowers or those that are ready to open and bugs will soon be pollinating. An insecticide should only be used as a last resort.
Speaking of flowers, some of the best ones to draw in even more useful insects are carrots, legumes (peas and bean flowers), members of the mustard family (including broccoli, cabbage, and Brussels sprouts), basil allowed to flower, dill, fennel, garlic chives, coriander, Queen’s Anne’s lace, milkweed, bee balm, coneflower, cosmos, sunflowers, asters, and verbena.
