Cabbage White Butterfly
Pieris rapae
The white butterfly whose green caterpillars chew through brassicas, often skeletonising leaves within days.
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Identify from a photoBackground
Introduced from Europe and now found across all Australian states, the cabbage white butterfly is the most common pest of home-grown brassicas. Adults are a familiar sight in vegetable gardens from spring through autumn. It is the caterpillar stage that causes the damage, chewing large irregular holes in leaves and burrowing into the hearts of cabbages and broccoli heads.
Adults lay pale yellow eggs singly on the underside of leaves. Because hot days bring continuous flights of adults, populations build rapidly and control has to be ongoing rather than one-off.
How to identify
- Adult: white butterfly, wingspan 40-50mm, with one or two dark spots on each forewing (female has two, male one)
- Eggs: pale yellow, bullet-shaped, laid singly on leaf undersides
- Larvae: velvety green caterpillars up to 30mm long, with a faint yellow stripe along the back
- Damage: large irregular holes chewed in leaves; caterpillars bore into cabbage and broccoli heads leaving dark frass
Life cycle
Egg to adult in 3-6 weeks in warm weather. Multiple overlapping generations from early spring until cool autumn weather slows flight activity.
Weather triggers
- Temperature: 12-32°C
- Adult flight peaks on warm sunny days. Caterpillar development fastest at 20-28C.
Peak season (southern hemisphere)
Red = active season · Dark red outlined = this month
Affected vegetables & crops
Click any crop to see current prices and growing info.
Climate zones at risk
Organic & low-impact control
- Fine vegetable netting draped over brassica beds from seedling stage
- Bacillus thuringiensis kurstaki (Btk, Dipel) sprayed on foliage. Kills caterpillars only, safe for bees
- Handpicking eggs and caterpillars while small
- White plastic decoy butterflies pegged around the bed. Reduces egg-laying because females avoid occupied territory
Chemical control
- Pyrethrum-based sprays for heavy infestations. Apply at dusk to reduce impact on pollinators
- Spinosad as a stronger option, still organic-registered
Always read product labels. Registrations change.
Prevention
- Cover all brassicas with insect exclusion netting before adults start flying
- Rotate brassica beds each year
- Check plants twice a week and crush any eggs found
Companion planting
Nasturtium can act as a trap crop. Butterflies often prefer to lay there. Strongly aromatic herbs (thyme, sage, rosemary) intercropped with brassicas slightly reduce egg-laying. Dill and fennel attract parasitic wasps that kill caterpillars.
Biosecurity
Widely established. No quarantine significance.
Know when Cabbage White Butterfly is actually about
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