Which garden insects are worth keeping around
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Knowing what you are looking at
The reason so many gardens end up on a spray schedule is that people can't tell one bug from another, so the safe move looks like killing all of them. The trouble with that is the predators breed slower than the pests do, so you knock everything back and the aphids are the first ones to come back, and now they've got nothing eating them.
So this is a post about identification rather than about pest control. If you can pick four or five of these out on sight you'll spray a lot less, and the spraying you do will be aimed at something.
The ones that look like nothing you would keep
Hoverfly larvae are the one people squash most often, because they look like a small pale maggot sliding along a leaf with no legs to speak of. They eat aphids, a lot of them, and the adult is the little wasp striped thing that hangs in the air over the flowers and can't sting you.
Lacewing larvae look like tiny brown alligators with pincers at the front, and some species carry a pile of debris on their backs, so you get a bit of fluff moving along a stem. They're some of the hungriest predators in a garden and they go through aphids, mites and small caterpillars.
Ladybird larvae look nothing like the adult. They're dark, elongated, a bit spiky and often with orange markings, and people think they're a pest because they're crawling all over the infested plant. They're crawling all over it because that's where dinner is.
The one ladybird that is not on your side
Not every ladybird eats other insects. The leaf eating ladybird has many more spots than the common ones, it's a duller orange with a slightly furry look to it, and it chews the surface off leaves on tomatoes, potatoes and pumpkins, leaving a lacy pattern behind. If you find a ladybird on a leaf that's been grazed rather than on a stem covered in aphids, have a closer look at it before you thank it.
The ones that are obvious once you know
Predatory wasps that lay eggs into caterpillars and aphids are tiny and you'll almost never see them at work, but you will see the result, which is an aphid gone a swollen papery bronze colour and stuck to the leaf. Those are called mummies and they mean the wasps are working, so leave that patch alone rather than spraying it.
Spiders in a garden are working for you full time, including the ones that build in among the beans and get in your face when you pick.
Praying mantises eat whatever walks past and that does include the odd useful insect, and on balance they're worth having.
What makes them stay
Predators turn up when there's something to eat, which means you have to tolerate a low level of pest for the good bugs to have a reason to hang around. A garden with zero aphids has zero ladybirds. That's the trade, and once you've made peace with it the whole thing gets easier.
Beyond that, most of the adults live on nectar and pollen even when their larvae are predators, so small flowers are what brings them in. Alyssum, marigolds, nasturtiums, dill and coriander allowed to flower, and anything in the carrot family that bolts. Plant them through the veggie patch rather than in a border away from it.
The other thing is to leave a bit of the garden untidy. A patch of mulch that never gets raked, a few stones, a plant that's gone over and hasn't been pulled out. That's where things overwinter and lay eggs, and a garden tidied to within an inch of its life has nowhere for any of it to live.
And put water out. A shallow dish with a few stones in it so nothing drowns is enough, and in a dry Strathalbyn summer it gets used constantly.
When you do have to spray
Sometimes a pest gets away from you and you need to knock it down. Two things make that less damaging. Pick the narrowest product that will do the job rather than the broadest, so an oil aimed at scale and aphids rather than something that kills everything with legs. And spray late in the day when the bees have finished, on the affected plant only, rather than blanketing the garden.
A broad spectrum insecticide sets the balance back weeks, so it's worth treating as the last move rather than the first.
Shop related products
- D.T. Brown Alyssum seed. Small flowers over a long season, and the adults love it.
- D.T. Brown Marigold seed. Easy to grow through a veggie bed.
- D.T. Brown Nasturtium seed. Sprawls, flowers hard and copes with poor soil.
- Multicrop EcoPest Oil. A narrower option for scale and aphids when you do have to spray.
Did you know we also stock a snail and slug barrier and a snail trap in the shop that aren't listed online, so give us a ring on (08) 8536 4333 to check what's on the shelf.
The seed rack and the pest control shelf are both in the garden centre, and if you bring in a photo or a leaf in a bag we'll have a go at telling you what you're dealing with.
More from the garden
- How to get good bugs into the garden and keep pests down
- Companion planting, flowers to grow with your vegetables
- 7 mistakes to avoid in a new vegetable garden
I am firmly on the side of the bees and I will absolutely stand in the driveway telling somebody about a hoverfly, so consider yourself warned.
Cheers,
Candeece
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