How to get hoverflies and lacewings into your garden
The two insects worth knowing by sight
If aphids keep coming back no matter how often you spray, the problem is usually that the spray is killing the things that were eating them. There are two insects worth learning to recognise, because between them they do most of the pest control in a backyard garden and neither one costs anything.
Hoverflies are the small yellow and black flies that hang dead still in mid air and then dart sideways. People swat them thinking they're wasps. The adult only eats nectar and pollen and is completely harmless, and it's the larva that does the work, a little legless maggot that looks a bit like a small green or brown slug on a leaf. It works through aphids steadily for the week or two before it pupates.
Lacewings are the pale green insects with clear veined wings that come to a light at night. Their larvae are flat and alligator shaped with visible jaws, and they're called aphid lions because of what they do to a colony. They take aphids, whitefly, thrips and mealybugs.
The mistake almost everyone makes
Both larvae look like pests. A hoverfly larva on a leaf surrounded by aphids gets blamed for the aphids, and it's the most useful thing in the bed. So before you reach for anything, have a proper look at what's actually on the plant, because the grub sitting in the middle of an aphid colony is usually the reason that colony has stopped growing.
That's worth 5 minutes of standing and staring. A colony with predators already in it will often collapse on its own within a week, and spraying it resets the whole thing, because the aphids come back from elsewhere faster than the predators do.
How you actually bring them in
The adults of both are nectar feeders with very short mouthparts, so they can't get into a deep tubular flower and they need small open ones. That single fact is the whole method, and it's why a garden full of big showy flowers can still have no hoverflies in it.
What works is the flat flowerheads made of dozens of tiny florets. Alyssum is the best of them and it's cheap, it self seeds and it flowers for months. Let a few herbs run up to flower rather than pulling them, because dill, coriander and parsley all throw exactly the right umbrella shaped head once they bolt, and a bolted coriander plant is more use to you flowering than it was as leaves.
Marigolds, cosmos and nasturtiums all pull their weight too, and the trick is having something in flower more or less continuously rather than one big burst, because the adults need feeding the whole time they're laying.
The part that's harder than the planting
Not spraying. A broad spectrum insecticide doesn't distinguish between an aphid and the larva eating it, and the soft bodied predators are usually hit harder than the pest because they're bigger and slower to recover. Even the gentle options matter here, since white oil works by smothering and it'll smother a lacewing larva just as happily as a scale insect.
None of which means never treating anything. It means treating the specific plant with the specific problem rather than the whole garden, and leaving the beds that are coping alone. Evening is the better time for it, when fewer beneficials are moving about. If you want the detail on where a spray does and doesn't belong, I've written that up separately in the Bug and Fungus Kill piece below.
The other thing that helps costs nothing at all. Leave a corner untidy. A bit of leaf litter or a stack of prunings in a corner gives lacewings somewhere to overwinter, and a garden that's spotless in July has nothing living in it in November.
Shop related products
- D.T. Brown Alyssum. The single best thing you can sow for hoverflies.
- D.T. Brown Cottage Garden Mixture. A spread of small open flowers over a long season.
- D.T. Brown Marigold Sparky Mixed. Easy to grow and long flowering in a veggie bed.
- D.T. Brown Nasturtium Jewel Mixed. Grows anywhere and doubles as a sacrificial aphid magnet.
Did you know the herb seed is on the rack in the garden centre rather than the website. Dill, coriander and the two parsleys are the ones to let flower, and they're all in the shop. Give us a ring on (08) 8536 4333 to check what's there, or browse the D.T. Brown seed range and the wider garden centre range.
Read next
- Brunnings Bug and Fungus Kill, and where not to use it
- David Grays Snail Pellets, and how to use them safely
- Brunnings Seed Raising Mix, and why seeds fail to sprout
I let the coriander bolt every time and tell people it's deliberate, which these days it very nearly is.
Cheers,
Candeece
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