As we head into spring, armies of tiny insects are moving into the garden. Contrary to popular belief, their arrival isn’t necessarily a bad thing. It can actually be a sign of a healthy, functioning ecosystem. Here’s why.
Although they can be annoying, all insects (even aphids) have a role to play in the garden. A few aphids on a rose aren’t necessarily something to panic about, and a few caterpillars nibbling on leaves don’t always warrant intervention. These pests are food for hoverfly larvae, ladybirds, lacewings and parasitic wasps, which in turn help maintain a healthy and diverse garden ecosystem and support pollination and food production.
Live and let pests live
It may seem counter-intuitive, but if you want a healthy garden, you need to stop spraying the first bug you see. Broad-spectrum insecticides don’t distinguish between pests and the insects that feed on them. Using insecticides indiscriminately can destroy not only pest populations but also the pollinators and predators that make a garden thrive. The result is a relatively sterile garden that is no longer teeming with life or supporting a healthy ecosystem. Sometimes, it’s important to leave a few of the bad guys around to bring in a lot of the good guys.
Build an army of predators
Ladybirds
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Ladybirds and their larvae absolutely adore munching on aphids. Before you go out and buy live ladybird kits, keep an eye on those small pockets of aphids and wait a few days to see if the ladybirds arrive themselves. These dainty little bugs might look pretty, but they’re mean machines when it comes to pest control, capable of devouring impressive numbers of aphids. |
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Better still, if you spot a black-and-orange, alligator-looking insect out and about, you’ve found a natural aphid eliminator. Ladybird larvae look nothing like their mums and dads, but they’re extremely efficient at reducing aphid populations in the garden. Where you find one ladybird larva, there are often more nearby. Look beneath leaves and amongst flowers for these little predators, and if you find them, leave them where they are or gently move them closer to an aphid-infested plant. |
Hoverflies
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They float like a butterfly, they’re striped like a bee, they have enormous fly eyes and, importantly, they’re completely sting-free. Hoverflies are an essential garden ally. Not only are they excellent pollinators, but their larvae are voracious predators of aphids and other small pests. Hoverflies are particularly valuable pollinators because they’re generalists, visiting a wide range of flowers rather than specialising in particular plants. Their ability to move between different plant species makes them important pollinators in both gardens and food production systems around the world. |
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Hoverfly larvae can do some serious damage to aphid populations. So, if you spot a tiny bee-like insect hovering around your roses or hellebores, leave them alone—they could be laying eggs nearby. Refrain from spraying if you can, as even natural and organic pest-control products can harm beneficial insects, including hoverfly eggs and larvae. |
Green Lacewing
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These delicate, winged insects are another great friend to have in the garden. Female green lacewings can lay hundreds of eggs during their lifetime, often attaching them to the underside of leaves on tiny stalks. Once they hatch, the larvae become formidable predators, feeding on small garden pests. |
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Lacewing larvae are not picky eaters. They’ll happily hunt aphids, two-spotted mites, scale, white flies and even mealybugs. A single lacewing larva can consume dozens of aphids in an hour, making them formidable little predators. And they’re rather ingenious hunters. Lacewing larvae will sometimes collect the remains of their prey and use them as camouflage, disguising themselves from potential prey, and giving new meaning to the phrase “a wolf in sheep’s clothing.” |
Parasitic wasps
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They may sound deadly, but parasitic wasps are harmless to humans and incredibly helpful in the garden. They’re called parasitic because they lay their eggs inside or on the bodies of other insects, which serve as hosts for their developing young. Once the larvae hatch, they feed on the host, eventually pupating inside or on its body before emerging as adult wasps. They then go on to repeat the cycle, quietly taking down garden pests from the inside out. It’s a miniature Trojan horse situation, if you will. |
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Parasitic wasps target a wide range of garden pests, including aphids, leaf miners, mealybugs, scale, stink bugs and caterpillars. Different species specialise in different hosts, making them an incredibly diverse group of natural pest controllers. A garden full of tiny parasitic wasps is a garden with its own pest-control department. They may occasionally find their way inside at night. If you find one buzzing around the house, gently usher it back outdoors rather than reaching for the fly spray. |
Planting for pollinators and predators
One of the best ways to encourage beneficial insects into the garden is to plant a diverse range of flowers that provide them with food and habitat. Don’t stop at bee-friendly seed mixes. Many predatory insects also need nectar and pollen to sustain them between meals.
Plants such as yarrow, Queen Anne’s lace, alyssum, dill, coriander and carrots left to flower are excellent choices. Their small, open flowers are particularly accessible to beneficial insects, providing a reliable source of nectar and pollen while adding diversity to the garden.
Attract pests by planting host plants such as nasturtiums and broad beans, and allow some of your brassicas to flower and set seed. These plants can act as sacrificial crops, providing a ready food source for pests while helping to attract the beneficial insects that prey on them. It’s a simple way to keep some of the action happening away from your prized plants.
Creating habitats for predatory insects
Planting a garden that welcomes pollinators and predatory insects is just the first step. To keep them around, you also need to provide safe places for them to shelter, rest and reproduce. A garden that offers food, water and undisturbed habitat is far more likely to support a thriving population of beneficial insects.
Create small pockets of habitat throughout the garden by incorporating:
- leaf litter
- mulch
- logs and sticks
- dense planting
- groundcover plants, and
- undisturbed corners.
These seemingly untidy spaces provide shelter from the elements and safe places for beneficial insects to rest, hide and reproduce. Resist the urge to tidy every last corner—sometimes, a little mess is exactly what a healthy garden needs.
Zombie aphids?
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A sure sign of a healthy garden is the appearance of brown, swollen aphids amongst a sea of otherwise green or black insects. These are essentially zombie aphids — aphids that have been parasitised by tiny wasps, which lay their eggs inside them. As the wasp larva develops, it feeds on the aphid from the inside, eventually killing it and turning its body into a papery, bronze-coloured shell known as an aphid mummy. Look closely and you may spot a small round hole in the back of the aphid. This means the adult parasitoid wasp has emerged from its host and flown off in search of another aphid to parasitise. Leave these little mummies where they are. They’re evidence that your garden’s natural pest-control team is hard at work. |
How to gently remove pests from your garden
Ants: the tiny farmers you do not want
Ants may look harmless (and they do play an important role in the garden ecosystem) but some species are remarkably effective farmers of sap-sucking insects. These wily little creatures tend aphids and scale, moving them around plants and protecting them from predators in exchange for their sweet, sticky honeydew.
So, instead of endlessly treating the aphids or scale, sometimes you need to address the ants. Take a closer look at plants suffering from aphids, scale or black sooty mould, and you may find an active ant trail leading straight to the source.
In some cases, what looks like an aphid or scale infestation is actually a symptom of a larger ant problem. Reduce the ant activity and you may find that natural predators can finally get to work, allowing the pest population to come back under control.
Focus on growing healthy plants
Pests are often more noticeable on plants that are struggling, and stressed plants can be less able to withstand or recover from pest damage. Before reaching for the sprays, take a closer look at the plant and consider why it might be languishing.
Consider:
- incorrect watering
- poor drainage
- drought
- excessive nitrogen
- compacted soil
- insufficient light
- inappropriate plant selection for the site.
Also consider whether your plants need more airflow and movement. Spring is a good time to prune back overgrowth, allowing more light and air to penetrate the canopy. Pruning also gives you the opportunity to inspect your plants closely, particularly the undersides of leaves and new growth, where pests often like to hide.
Sometimes, the best pest control is simply giving a plant the conditions it needs to thrive.
Manual removal of pests
Sometimes, the simplest approach is the most effective. A good blast of water can dislodge aphids and knock their numbers back, while scale can be scraped from stems and leaves by hand. You can also remove host plants that have served their purpose or prune away heavily infested branches.
These tasks may seem mundane, but there’s something surprisingly satisfying about physically removing pests from your plants. It may take a few weeks of regular attention to get populations back under control, but the payoff is a healthier, happier garden.
When to use sprays
Sometimes manually removing pests simply isn’t practical, and depending on the season and weather, beneficial insects may be in short supply. If pest populations are causing significant damage to your plants or crops, it may be time to consider using an insecticide.
The key is to treat insecticides as a last resort rather than the first line of defence. If you do need to intervene, choose the most targeted option available and apply it carefully to minimise harm to beneficial insects.
For example, if wood-boring insects have taken hold in a fruit tree and are affecting its health or fruit production, this may be a situation where using a treatment you would otherwise avoid is warranted. The goal isn’t to maintain a completely pest-free garden, it’s to step in when pest pressure has tipped the balance too far.
Before you spray
- Identify the pest
- Check the damage
- Look for predators
- Try physical control
- Fix the underlying problem
- Treat only if necessary.
A garden in balance
A healthy garden isn’t one without pests. It’s one where pests are part of a much bigger system.
Give predators somewhere to live. Give them something to eat. Don’t spray them out of existence. Plant for diversity, keep an eye on your plants and intervene when you genuinely need to.
You might never completely eliminate aphids, scale or caterpillars, and that’s okay. A garden teeming with life isn’t going to be perfectly spotless. The goal isn’t to eradicate every pest. It’s to create an ecosystem where no single pest is allowed to take over.
So the next time you spot a few aphids on your roses, don’t panic. Take a closer look. There might be a ladybird larva hiding among them, a hoverfly laying eggs nearby or a tiny parasitic wasp already at work. Sometimes the best thing you can do for your garden is give nature a little time to do the job for you.
