Do you have a problem with pests in your garden? If so, you’ve probably wracked your brains trying to get rid of them and maybe even thought about using toxic pesticides. There’s another solution at your disposal, however: beneficial insects. Read on to learn about these completely safe, low-cost natural predators and how you can attract and use them in the garden.
What Are Beneficial Insects?
Beneficial insects are insects that eat other insects and pests, like slugs and snails. You can attract them to your garden or even purchase them and apply them to eat less desirable insects that are destroying your plants or eating fruits and vegetables. In commercial agriculture and horticulture, beneficial insects are part of IPM (integrated pest management), a strategy that attempts to use multiple solutions to solve pest problems beyond simply using chemical pesticides.
What Are the Benefits of Using Predator Insects?
There are numerous benefits to using natural predators in your garden. First, insects have been eating other insects since they first appeared on the earth, so this is nature’s way of balancing the environment. It’s only been since the latter part of the 20th Century that humans disrupted that balance by using chemical pesticides and introducing plants that don’t have innate resistance to pests.
Using beneficial insects, when done correctly, could mean you don’t have to use any harmful chemical pesticides in your garden at all. Many pesticides, even those deemed “safe” on their labels, have unwanted long-term health consequences. Their use is predicated on the person applying them wearing gloves, masks, etc., and not getting any of the chemicals on their skin. But what happens when your children or pets play in the yard? What about food that has been grown with pesticides? Do you really want that going into your diet?
Going pesticide-free can also save you money and won’t contribute to any other contamination of the environment, such as leaching into the ground water or killing birds, bees, butterflies and dragonflies–all elements you want in your garden.
Insects have also been developing pesticide resistance over the last several decades. There are now over 500 species that don’t respond to pesticide application at all. You could be using all those chemicals and only encouraging stronger bugs!
Furthermore, many good insects, like the ones discussed below, get wiped out too when you use broad-spectrum pesticides. Ironically, you could be making your garden even more susceptible to pests by using chemical pesticides.
How Do You Get Started with Natural Predators?
The first thing you need to do when considering using natural predators in your garden is to identify which insects are a problem and which ones are fine to let be. If you can’t identify insects easily while on the plants, try trapping them for later identification. You can purchase insect traps online or at your local garden center. Use garden books, online resources, your area nursery or a nearby university agriculture extension department to help you figure out what you’re dealing with.
Next, determine which types of beneficial insects are the best for the type of problem you have (see profiles for different predator insects below). If the types of insects you want in your garden are native to your area, you can take steps to attract them naturally (see below).
If they are not present in your region but could be supported in your climate and geography, you can purchase beneficial insects online and have them shipped to you. Make sure to follow the directions for their storage and release carefully. Insects can be fragile and need the right outdoor temperatures to survive. Also, you may need to delay the development of larvae turning into adults by keeping the insects in your refrigerator until you have the right conditions for their release.
How Do You Support Beneficial Insects in the Garden?
Even if you initially buy predator insects to release in your garden, you’ll need to support them so they thrive and stay there. The same things that attract beneficial insects to your yard or farm are the elements that keep them there long-term.
A major element in keeping good insects happy is providing them with the right habitat. You don’t want to just leave them to bare ground, as this exposes them too much to sun and wind. If you have unplanted areas, be sure to cover them with mulch, or use ground cover. This will shelter your beneficial insects and hold moisture for them, as well as provide food as it decays.
If you have very large areas that would normally lie fallow, especially in winter, try using cover crops there instead. Some common favorites include:
- fava beans
- sweet clover
- red clover
- white clover
Instead of tilling these crops under at the end of the season, leave them in place to provide a safe harbor for beneficial predators. Also, be sure to overlap your cover crops with your food planting areas, so beneficial insects can easily hop from one section to another. If you leave a gap in between, they may not make it to the area you are targeting for their predation.
Another way to attract and keep beneficial predators is to attach a strip of perennial vegetation to areas that are hoed, turned over, tilled or replanted frequently, whether crop lands or annual beds. This affords beneficial insects a safe place to live when the areas they are “patrolling” are in transition.
While hedgerows may have gone out of style with the general public, they’re back in a big way for gardeners using integrated pest management. In addition to providing privacy and boundaries, they offer habitat for desirable insects. You need to think beyond your current growing season and and provide a location for beneficial insects to overwinter and a long-term source of food. Whether you plant trees, shrubs or flowers, try to have something blooming all the time for an easy way for your insects to obtain pollen and nectar.
What Do Beneficial Insects Eat Besides Other Insects?
Your beneficial predators will need additional sources of nutrition besides the bad bugs they eat. Most insects need at least two other dietary items: protein and sugar. Protein, which they obtain from pollen-producing plants, aids in their egg development. This is a necessary ingredient if you want your beneficial insects to stay around for multiple generations.
Insects also need sugar for fuel, and they primarily get this from nectar-bearing plants with small flowers. Examples of what you could plant to feed beneficials include yarrow, parsley, dill, wild carrot, cilantro, alyssum, mustards and members of the daisy family, like asters and cosmos.
Beneficial insects will do better if you plant some species with extrafloral nectaries too–glands apart from flowers that produce nectar. Plants with extra floral nectaries include willows, peaches, plums, morning glories, peonies, elderberries, vetch and sunflowers.
You can create your own nectar too. Mix 3/4 cup of sugar with one quart of water, and spray it directly on your plants. Make sure your solution is always fresh.
What Are the Most Common and Effective Beneficial Insects?
Here’s a look at 12 common insects used to eliminate less desirable insects. Some of them are available for purchase in quantities, so if you don’t already have them in your garden and can’t attract them, you can buy them and give them a new home.
Braconid wasps are great for eliminating unwanted moths, beetles and aphids from the garden. The adult female kills its host by injecting her eggs inside it, where the larvae can feed on it and ultimately cause its demise. This insect is very attracted to nectar-producing plants.
Damsel bugs feed on thrips, leafhoppers and caterpillars. If you have an alfalfa field near you, you may be able to catch some with a net and release them into your garden.
Green lacewings are one of the most popular beneficial insects because of their effectiveness. While adult lacewings eat insects, the larvae (known as “aphid lions”) are particularly voracious. They devour whiteflies, thrips, scales, mealybugs, caterpillars and aphids with great speed. You can attract them by growing coreopsis, sweet alyssum or cosmos, although they are also readily available by mail order. If you release green lacewings that you have purchased, they will be in egg form.
Minute Pirate Bug
These insects eat most any other insect, but they especially love the larvae of moths, grasshoppers and beetles. To support their presence in your yard, grow yarrow, goldenrod daisies or alfalfa.
Spined Soldier Bug
Spined soldier bugs look like common stinkbugs, but they have distinctive pointed “shoulders” that help you tell the difference between them. They eat beetle larvae and hairless caterpillars, as well as earwigs and grasshoppers. They need long-term shelter for survival and do well in perennial gardens.
With aphid midges it’s the larvae who are the predators. They feed on more than 60 different species of aphid and paralyze them with their toxic saliva. They have a high protein need, so pollen plants are essential to their well being.
There are over 2,500 species of ground beetles! These nocturnal predators not only eat cutworms, cabbage maggots, asparagus beetles and Colorado potato beetles (all soil-dwelling insects), they will rid you of slugs and snails as well. Some species even eat weed seeds. They like a stable habitat, such as a perennial garden, and in orchards they gravitate towards white clover.
Lady beetles (AKA ladybugs) have 200 different species in North America alone. Both adults and larvae eat mites, leafhoppers, aphids, mealy bugs and insect eggs. One lady beetle can eat 50-60 aphids per day. You can attract them with dill, yarrow, fennel and coreopsis, or buy them as adults to release into your garden. While most people are familiar with the spotted appearance of the adult lady beetle, you may be surprised to see that their larvae look like tiny alligators.
Soldier beetles eat aphids and caterpillars, but be careful with these predators, as they will also consume some beneficial insects as well. They are attracted to catnip, goldenrod and hydrangea.
Nematodes kill soil-dwelling insects. There are several species that are used as beneficial predators, so you have to choose the right one for your particular garden pests. For a garden of roughly 3,200 square feet, you’ll need about ten million nematodes! They are a popular online purchase. Apply them as juveniles any time temperatures are over 45 degrees Fahrenheit during the day.
There are 1,300 species of Tachinid flies. They may look like common houseflies, but they are far more helpful in the garden. The larvae of this insect burrow into caterpillars, destroying them from the inside out. They are drawn to dill, parsley, herbs and sweet clover.
The Praying Mantis has always been a fascinating predator to watch in action. They eat aphids, beetles, leafhoppers, caterpillars and even mosquitoes. Some gardeners have even been able to entice them to eat small bits of meat out of their hands. This is another species that is frequently purchased for application in the garden. You buy them by the egg case, each case containing about 200 baby mantids. Three egg cases will adequately cover 5,000 square feet.
Once you establish beneficial predator insects in your garden, you’ll be able to enjoy their services for many insect generations to come. Think about how much money you can save over the seasons, as well as how much you will preserve your family’s health and the environment, by not using chemical pesticides. When your roses are free of thrips and your vegetable plot rid of beetles, you’ll be happy you chose beneficial insects to handle your pest problem.