Put Beneficial Insects to Work in Your Garden: Here’s How

Tiny wasp feeding on pollen on a daisy — A tiny wasp feeding on the pollen of a daisy, which offers a good landing pad for insects.

This page contains affiliate links.*

Home » Put Beneficial Insects to Work in Your Garden

When you have an insect pest infestation in your garden or landscape, there’s an army of predators ready to take them on. If you don’t kill them first.

These predators are called ‘beneficial insects’. And they need three simple things to survive in your garden: pest insects, flowers, and some water.

Insect lives typically have four stages: egg, larva, pupa, and adult.

When a female beneficial insect is ready to lay her eggs she looks for a pest insect infestation and lays them nearby, or in the pest insect. That way she knows her babies will be able to easily find food when they hatch.

Then the young babies start eating those pest insects and grow nice and big and fat. Then they’re ready to pupate to turn into adults.

When the new adults emerge, their next task is to find flowers that will provide them with nectar and pollen so they’ll have the nutrition and energy to mate. Then the females will find a place to lay their eggs.

On this page

Insect Carnivores

Fat caterpillar with little white eggs attached all over it — Tomato hornworm with little white parasitic wasp eggs stuck to it. Credit: Wikimedia Commons

These beneficial insects are carnivores. They eat insect ‘meat’, usually in their larval stage.

Depending on which carnivorous beneficial insect it is, the mother may lay her eggs on a leaf where there are pest insects feeding on leaves. Or they may lay their eggs in or on another insect, like an aphid or a caterpillar.

When the eggs are laid near a pest infestation, the hatched larvae crawl over to the pest insects and start eating them. Like a ladybug larva that devours aphids.

When the eggs are laid in a caterpillar, the hatched larvae eat the insides of the caterpillar, killing it. Like tiny tachinid flies devouring a tomato hornworm, from the inside (see photo). Then they pupate and emerge from the shell of the hornworm as adults.

Not all the beneficial insects operate the same way. Some eat other insects in their larval and their adult stage. Like the ladybug.

But most need pollen and/or nectar to complete their diet. And not just any flowers will do. Like how pollinators need certain flowers, the same is true for the beneficial insects. Which makes the beneficial insects pollinators, too! But first…

Let’s see who’s working for you in your garden

It takes some keen observation to find all these helpful bugs, but knowing what they look like gets you started. Attracting Beneficial Bugs to Your Garden* by Jessica Walliser has great information and photos of the good bugs.

To see some of them, having a hand lens or a magnifying glass handy will help you see a new world in action in your garden. (Please beware of getting sun rays into your eye through the hand lens!) But many fly and flit around fast so it can be difficult to take a good look. But If they’re tiny and moving fast, they could very well be powerful beneficial insects.

Green lacewing on a leaf — Green lacewing, a beneficial whose larvae gobble up aphids Credit: Katja Schulz

Meet some of the beneficial insects:

Parasitic wasps (they don’t sting us, and some are very tiny), lacewings, ladybugs, some beetles, predatory mites (they eat other mites), true bugs, true flies (like hover flies, spiders (please get over this fear), mantids… and more.

Corn leaf with many aphids on the underside with lacewing eggs, tiny while ovals at the end of long threads sticking out from the leaf

Little lacewing larva is gobbling up aphids on the corn leaf in my garden.

Corn leaf is mostly clean of the aphids with one lacewing larva still eating — Corn leaf is mostly clean of the aphids with a lacewing larva still eating. The eggs are mostly hatched and the aphid population went down to just a few

Now, let’s see who’s eating your plants:

These are the insects (and mollusks) that eat foliage, or roots: Aphids, spider mites, scale, caterpillars, slugs and snails, thrips, grasshoppers, whiteflies, psyllids, pest beetles, mealy bugs, corn earworms, and more.

The Organic Gardener’s Handbook of Natural Pest and Disease Control* from Rodale is an excellent resource to help you identify your pests, and diseases, and all the measures you can take to solve garden problems. It’s an old book but still very relevant and revered.

What happens when you kill the pests?

When you spray with a pesticide, whether it’s a synthetic or a natural one, you also kill the beneficial insects that are present. And even though you kill the pests, any beneficials that remain are left without their food source. New babies won’t mature, so your landscape’s beneficial insect population declines and the pests that survive the spraying or that come in later have fewer enemies to keep them in check. The beneficials need more time to catch up. So you have your pest cycle all over again. Which means more control work for you, and so on. Not to mention the impact spraying has on the pollinator populations.

But you can have your garden and landscape plants under full control of beneficial insects, avoid the trouble of spraying, reduce using other pest control measures, and avoid harming the pollinators this whole planet needs for survival. Instead, maintain a healthy population of the insects whose very job it is to consume populations of pest insects.

The three things that beneficials need

There are three things you need to do to let this beautiful, powerful process handle your pest control for you.

First, when you find a pest infestation, don’t panic. This will attract beneficial insects. And the method Mother Nature has devised to attract them is a process of gorgeous, amazing complexity…

You see, insects are receptive to scents that inform them and influence their behavior. When plants get eaten by pest insects, they send out scents that signal the situation and that attracts the right type of predator insect to the type of prey that’s on them. Read Plants’ Answer to Bug Attack: Call a Predator and Plants can detect insect attacks by ‘sniffing’ each other’s aromas for more info.

In other words, the plant that’s getting eaten calls the right bugs for help with that problem. And it works.

So let the pests build a population, don’t panic, and the beneficials will come and clean it up. Yes it may be daunting and sometimes it is wise to take other measures, like hand-picking pests, or hosing them off with a water spray, or trapping and killing slugs, snails, earwigs, or sow bugs.

The other two things your garden needs is water and flowers that feed the beneficials.

For water, I overhead water and some hangs onto the foliage and flowers and is enjoyed by insects. Plus I set out glazed saucers to catch more of the sprinkler’s water.

For flowers, many flowers will do but there are certain types that are most effective to attract and feed beneficial insects.

The flowers that attract the beneficials

Ok, now you have a great excuse for having a flower garden! Some of these flowers are good as cutting flowers, and most are good for the pollinators, too. And as the pollinators need different nutrients, different flowers have different ingredients in their nectar.

Nectar isn’t all sugar water—not at all! It also has amino acids, lipids, stimulants, organic acids, proteins, and even microbes. You want a diversity of the right flowers; the best fed beneficials are the ones who can do more pest control and make more babies. Ain to have a variety of blooms throughout the season to keep a steady supply of floral food.

Heliopsis, Shasta daisies, Crocosmia, native buckwheat (Eriogonum species), annual buckwheat as a soil builder in annual garden beds, daisies, mountain mint (Pycnanthemum), all oreganos, sweet alysum, black-eyed susans, calamint, cilantro, dill, fennel, feverfew, goldenrod, cosmos, coreopsis, Echinaceas, asters, sunflowers, verbena, and yarrow are all good choices.

Fortify your garden with beneficial insects by planting a variety of flowers attractive to them. Like for pollinators, native flowers are a big plus.

A great book on attracting beneficials is : Attracting Beneficial Bugs to Your Garden* by Jessica Walliser.

A flat cluster of tiny yellow flowers with a tiny wasp on them. — A tiny parasitic wasp is feeding on nectar from a fennel flower.

Large parasitic wasp with a long ovopositor is feeding on yellow fennel flowers. — This large parasitic wasp has a long ovopositor to lay eggs in its prey.

The aphid infestation that frightened me

I’ve had landscapes and gardens for decades and never had any pest problems. I’ve always had a variety of flowers just because I liked to grow them and cut them. Being an organic grower, I never would have sprayed anything.

The one time I felt I might need to resort to some kind of insecticide was when I notice curling on the leaves of my Santa Rosa plum tree. It was spring. Looking closer at the underside of the leaves, I found a phenomenal number of aphids all sucking away in unison! Shocked, fear drove my thoughts into what non-toxic or even toxic poison should I use to stop this.

But I also noticed adult ladybugs, larval ladybugs, ladybug pupae, ladybug eggs, and soldier beetles. So I thought…I hope they can handle this infestation.

I had young children then and was quickly distracted. About two weeks later I went out to check on the plum tree. Not one single aphid. Clean as a whistle. The curled leaves were still curled, but they were getting buried in new growth.

This works. Let it work for you in your landscape.

Observe them, and have fun doing it!

Start looking for the beneficial insects in your garden. Get a hand lens or a magnifying glass to help you see them. (Please beware to not let sunlight through the glass and into your eye… or onto the flowers and bugs! :-0)

A flower on a cilantro, dill, or parsley plant attracts many, many parasitic wasps. It’s fascinating to just sit in the garden and watch them flit around. Many of them are so tiny they’re barely visible. I guarantee they’ll be there. See if you can find lacewings, hoverflies, and even ladybugs or their eggs or larvae on your flowers or near your aphids. And don’t forget some of the beetles in the soil are helping, too.

Caveats

An exception to this whole system is when there is a non-native invader pest species. Sometimes these need specific pesticide treatment, and often a specific predator will work.

Please note that I don’t recommend to go out and buy beneficial insects. Often there are ladybugs and praying mantids for sale in the spring. The praying mantids they sell are voracious, indiscriminate eaters, they’ll eat any and all insects, including the beneficials you already have. Plus, they’re not native to North America and they can disturb your local insect ecology. For ladybugs… just keep some aphids around! 😉 But there are other beneficials available from some sources. Often they’re best for farmers or to use where there are very low insect populations.

More Information and flowers

The Organic Gardener’s Handbook of Natural Pest and Disease Control*, from Rodale, Rodale Inc., 2009 gives loads of ID and info on pests and diseases with their solutions and natural enemies.

For lots more information and details about this truly fascinating topic, read this book: Attracting Beneficial Bugs to Your Garden*, by Jessica Walliser, Cool Springs Press, 2022. It has the photos for you to ID the beneficials in your garden.