Beneficial insect
Ladybird
The aphid vacuum every garden wants, and its ugly larva does most of the work.
One larva eats 400+ aphids before it pupates.
How to spot it (and its larva)
The adult is the one everyone knows: a domed 6–10 mm beetle, usually red or orange with black spots (spot count varies by species and doesn't tell you age). What most gardeners don't recognize is the larva: a tiny, spiky, blue-black alligator-shaped crawler with orange markings. It looks like a pest and gets squashed by mistake, which is a tragedy: the larva is a far hungrier predator than the adult.
Look-alike warning: the invasive-looking larvae are the good guys. If you find spiky crawlers on a plant that's covered in aphids, leave them, and they clear the colony for you.
What it hunts
The pests it clears for you. Tap any one for the full identify-and-control guide.
How to invite it in
You don't buy most beneficials. You build the habitat that keeps a wild population breeding on-site. Do these and they come, and stay.
- Plant tiny-flowered umbels and daisies
Adults need pollen and nectar to lay eggs. Dill, fennel, cilantro left to bolt, yarrow, alyssum, and cosmos keep them in the garden between aphid outbreaks.
- Leave a few aphids alive
A garden scrubbed spotless has no prey, so the predators leave. Tolerating a light aphid load on a sacrificial plant keeps a resident ladybug population fed and breeding.
- Give them a drink
A shallow dish with pebbles for a landing pad, refilled in dry spells, keeps beneficials from moving on to a wetter yard.
Plants and habitat that bring them in
Small-flowered plants feed the adults so they stay and breed. A packet of these does more for lasting control than a bag of mail-order bugs.
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Don't undo it
The fastest way to lose a beneficial is a broad-spectrum spray. It kills the predators faster than the pests and triggers a worse rebound.
- Broad-spectrum insecticides (including many 'organic' pyrethrins) kill the larvae faster than the aphids and trigger a worse rebound
- Squashing the spiky larvae by mistake. Learn the shape, it's your hardest worker
- Blasting every aphid off with a hose before the colony can feed a single larva
Should you buy them?
Buying bagged adult ladybugs is mostly money down the drain. They are wild-collected, often dehydrated, and simply fly away within a day. Build habitat instead. If you must buy, refrigerate them and release at dusk onto a watered, aphid-heavy plant to slow the exodus.
Questions about ladybirds
Do ladybugs I buy in a bag actually stay in my garden?+
Usually not. Bagged adults are wild-caught and fly off within a day or two. You get far better, lasting control by planting the flowers that keep a wild population breeding on-site.
What's the spiky little alligator-looking bug on my aphid-covered plant?+
That's a ladybug larva, and it's the best thing you could find there. It eats more aphids than the adult. Leave it alone and let it clear the colony.
Plan a garden good bugs want to live in
PlotToTable sizes your beds, spaces every crop for airflow, and flags the pests that hit what you grow, so the predators that eat them have a reason to stay.