Cabbage White Butterflies – How to Avoid a Brassica Massacre

, written by Ann Marie Hendry gb flag

Cabbage white butterfly

Like many gardeners, I've been unfortunate enough to experience some brassica damage in the past. A few tattered swedes, a holey kale plant – tell-tale signs that Small Cabbage White butterflies had laid their eggs on my plants. I considered the damage annoying, but it never reached really troublesome proportions in my garden.

Last year when I spotted large numbers of Cabbage Whites flying around, I didn't pay much attention to them at first, as I had (fortunately, as it turned out) decided not to grow any brassica crops. I do grow nasturtiums along the vegetable patch fence however, and within a matter of days I went from 'Oh look – that's an interesting caterpillar' to 'Eek! What are those caterpillars and what have they done to my nasturtiums?'

Large and Small Cabbage White Butterflies

It turns out that the Small Cabbage White butterfly, while undoubtedly a pest, is nothing compared to its big brother, the unimaginatively-named Large Cabbage White. The two are very similar, but the caterpillars are distinct – the Small Whites are an unassuming pale green colour, while the Large White larvae sport a hairy black and yellow jacket.

Small cabbage white caterpillars (cabbage worms)

Both butterflies are widespread throughout Britain and Europe, and the Small White has also been introduced to North America, Australia and New Zealand (sorry guys!), where it's often known as the 'imported cabbageworm'. If it's any consolation, the Small White is less of a voracious feeder than the Large White – as I discovered, when half a dozen robust nasturtiums were reduced to skeletons.

As the name suggests, cabbages and other brassicas are the favoured food plants of the Cabbage White larvae. The butterfly will lay eggs on the undersides of leaves (singly in the case of the Small White, in groups of 40-100 by the Large White) and after a week or two the larvae will emerge, like the Very Hungry Caterpillar in my favourite childrens' book, ready to eat whatever lies in its path. Small Whites will tunnel into the hearts of cabbages, so even if they're around in fewer numbers, a handful of larvae can still do serious damage to your crop.

Protecting Against Cabbage Whites

So how do we stop them from destroying our crops? Well, prevention is always better than cure, so the first step is to invest in some good, butterfly-proof netting. I've draped mine over hoops to make it easy to throw it back for weeding or harvesting, but you can lay it directly on top of the plants.

Small cabbage white caterpillar damage

Make sure the barrier is firmly held down at the edges, with no gaps that butterflies could squeeze in through – I prefer to use bricks rather than pegs, which tend to tear netting and shorten its life. Alternatively, burying the edges into the soil will make absolutely sure that there are no gaps.

You can use the Netting icons in our Garden Planner to mark on your plan where you need it in your garden. If you're not sure which of your crops are likely to be affected, use the Custom Filter button to show only brassicas in the selection bar, and group these together under your netting.

Cabbage Whites produce two broods per year (three in a favourable summer), so make sure to install the netting in spring and don't remove it until autumn. Even under netting however, regular inspection of leaves is essential. Hand-picking eggs and larvae off the plants can be laborious, but it is effective. Small White larvae are well-camouflaged, so make sure to check the ribs of leaves where they often hide. Growing red-leaved varieties of cabbage and other brassicas can make it easier to spot them.

Cabbage white butterfly

Cabbage White Predators

As any organic gardener knows, encouraging natural predators is a great way to control pest populations (and saves you having to perform grisly executions personally). Cabbage white larvae have a trick up their sleeves though – they accumulate mustard oil in their bodies from the food plant, which makes them unpalatable to most predators. Some birds will still eat them however, so it's worth providing feeders and nest boxes to encourage insectivorous birds such as house sparrows, goldfinches and skylarks into your garden.

Large White caterpillars can fall prey to the larvae of Apanteles glomeratus, a parasitic wasp, which devours the caterpillar from the inside out, carefully avoiding the vital organs so the host continues to grow to full size. If you find any dead caterpillars with yellow cocoons next to them, it might be worth moving them among your brassicas so that the parasites will attack further generations.

Once fully grown, the larvae will move away from the food plants and make their way to somewhere sheltered such as a fence, shed wall, or tree trunk, and pupate for around two weeks in summer, or eight weeks for overwintering pupae, so it's a good idea to check these areas and remove any you find.

Surprisingly considering the devastation wreaked on my nasturtiums I didn't find a single pupa over the winter, but spiders seemed to have a feast on the larvae last year and I've seen butterflies caught in their webs this year too.

Despite the likelihood of total annihilation, I am growing nasturtiums again – hopefully their presence will distract the butterflies from trying to squeeze in under my netting and I'll enjoy a good crop of broccoli later this summer!

By Ann Marie Hendry.

Bugs, Beneficial Insects and Plant Diseases

< All Guides

Garden Planning Apps

If you need help designing your vegetable garden, try our Vegetable Garden Planner (for PC & Mac) or if you'd prefer an app for your mobile or tablet device, our iPad & iPhone app Garden Plan Pro is available on the App Store here.
Garden Planning Apps and Software

Vegetable Garden Pest Warnings

Want to Receive Alerts When Pests are Heading Your Way?

If you've seen any pests or beneficial insects in your garden in the past few days please report them to The Big Bug Hunt and help create a warning system to alert you when bugs are heading your way.

Show Comments



Comments

 
"my cabbage is attacked by very tiny flies...Black dots like. and also I saw someclusters of white dots like things and when I touched them they were like ashes :( what to do now....any home remedies?"
babra on Thursday 19 February 2015
"Hi Babra, I'm not sure what's affecting your cabbage I'm afraid (aphids perhaps?) but I'd recommend hand-picking all of them off (or use a jet from a hose to dislodge them) and then protect your plants with netting so insects can't get near them. I hope that helps!"
Ann Marie Hendry on Friday 20 February 2015
"thx ann for ur suggestion... I will try that :)"
babra on Sunday 22 February 2015
"Hi babra my names dave what u have on your cabbage is blackfly and white fly they suck the sap from the plant and stops it growing my cure is a spray bottle with a little dish soap thos will not harm the plant's and you will need to do this every three days hope this helps"
david on Friday 27 February 2015
"Thanks for a very interesting article on cabbage white butterfly. I intend to cover my young cabbages with a net but I wanted to ask you what experiences you have about the butterflies flying low...? I note that you put your netting right down to the ground. If I left a 15 cm gap at the bottom, do you think they would get underneath? Thanks again for a really informative web site! "
Sally on Tuesday 17 November 2015
"Hi Sally, sorry for this extremely tardy reply! The netting really does need to be right to the ground, with the edges securely weighed down or buried in the soil."
Ann Marie Hendry on Wednesday 18 May 2016
"What ever happened to using Sevin or Eight?? I always plant my cabbages where I can see them from the door, then when I see the butterflies, I sprinkle it. "
C.J. on Thursday 2 June 2016
"There have been a couple studies done about using upland cress as a dead end trap crop for the cabbage white. They prefer to lay their eggs on the upland cress, but then the caterpillars can't eat it so they die. This is the first year I've used it, but I haven't seen a tenth of the caterpillars I have in years past."
Sara (Zone 5) on Tuesday 28 June 2016
"I saw many cabbage whites laying eggs on my brassicas this year, but no caterpillars - I think they must have all been taken by the wasps which were constantly patrolling the garden."
John on Friday 16 December 2016
"There's a very good chance you're right John. What many people don't realise is that wasps feed meaty morsels to their young, and in doing so make an extremely valuable contribution to garden pest control."
Ann Marie Hendry on Friday 16 December 2016
"That's an interesting insight Sara. I believe upland cress is also known as land cress, and it's easily available from seed companies. I may have to try that - thanks for sharing!"
Ann Marie Hendry on Friday 16 December 2016
"Hi do you post to Australia? thank you David"
david on Sunday 12 March 2017
"Hi David, we don't sell any physical products. Our garden planning apps (click the Planner link in the menu bar at the top of the page) will work in Australia however."
Ann Marie Hendry on Wednesday 15 March 2017
"I wouldn't advise laying the netting directly on the plants, as the cabbage whites will just lay their eggs through the net onto the leaves of your brassicas, even sticking their abdomens through to reach a leaf just below or inside the net. It should be kept at some distance from the leaves in all directions on a frame of some kind."
John on Tuesday 2 May 2017
"Indeed John - I cut down yellow gas pipe to make hoops to drape netting over, and many people use the blue water pipe, which is very similar. Alternatively, any metal or wooden structure can be used as long as there are no sharp corners. For the simplest solution, use bamboo canes with flowerpots or burst tennis balls over the ends to stop the canes poking through the netting."
Ann Marie Hendry on Tuesday 2 May 2017
"When do cabbage white butterflies appear"
Keith Boden on Friday 23 June 2017
"I'm in Cornwall near St Ives. The last few years although I haven't seen butterflies I've found caterpillars on my brassicas throughout the winter. They look like cabbage white but are very large only one or 2 at a time. Will be getting netting and will keep it up year round. It's surprising how much damage just one or two of them can make."
Carol Ann on Saturday 24 June 2017
"Will need oil or diatomaceous earth help with these cabbage white butterflies?"
Deborah Butcher on Sunday 25 June 2017
"What time of year do cabbage whites appear? my netting is fit to burst now and i'm wondering should i remove it as the plants are already well established? Thanks"
Dom on Monday 26 June 2017
"1st Cabbage White Butterfly seeen in garden in Shenstone, Sth Staffs. 3rd July and another today 5th. Too late. Picked me first cabbage yesterday. Untouched by the little bu**ers!"
Keith Boden on Wednesday 5 July 2017
"Yes I see them now, loads of them and they are inside my netting (my netting is bursting at the edges...note to self, bigger netting next year!), im using a shoot to kill policy all over the garden...im making room for red admirals and the like!"
Dom on Wednesday 5 July 2017
"Hi Keith, that's interesting - I haven't seen them here yet, but I'm a bit further north than you, in the south of Scotland. Please do report any sightings of pests (and beneficial insects too) at www.BigBugHunt.com - we're working to create a pest prediction service which will use data provided by gardeners about when and where bugs are seen to advise when bugs are likely to appear in your area."
Ann Marie Hendry on Wednesday 5 July 2017
"Our nasturtiums are being eaten by a swarm of large cabbage catepillars We have courgettes in the same bed should we be worried about them ?"
Janet on Wednesday 26 July 2017
"The caterpillars of cabbage white butterflies will only feed on cabbage family plants Janet. This includes nasturtiums unfortunately. Your courgettes will be safe!"
Ann Marie Hendry on Wednesday 26 July 2017
"I nhave used a net to try and keep the cabbage whites at bay. I put poles aruond the crop then placed plastic milk bottles over these then the net. This prevents holes etc,"
Graham on Sunday 13 August 2017
"Hallo, I just stranded growing vegetables on my small balcony so am very much the novice. I have two broccoli plants in two separate pots doing very well. This said I've noticed that a few of the lower leaves have what looks like ringworm. By this I mean white squiggly lines over the leaves. On closer inspection I found a few small white lumps at the end of these lines. The leaves are in no way eaten from the outside. Rather this worm is in the leaf itself. I've since removed the leaves and am keen to hear what this might be and how I might protect the plants against it using natural remedies. Many thanks. "
Scott Blick on Friday 8 June 2018
"Going on from my comment last year about cabbage white b/flies, this year is weird. Saw quite a few in mid May, hence I built a cabbage cover. However nothing since then. Have they been and gone or are we awaiting the July massacre? I'm in Sth Staffs. Don'y let your guard go down guys."
Keith Boden on Monday 11 June 2018
"Last year I planted 4 brussel sprout plants next to 8 curly kale plants. Having never grown brassicas before I had no knowledge of Cabbage White caterpillars and therefore did not cover any of them with netting. It wasn't long before I spotted loads of caterpillars munching their way through the brussel sprout leaves. However, there were absolutely none on the kale plants. So they obviously 100% preferred the brussels which ended up being sacrificial plants by accident! "
Simon O'Connor on Thursday 14 June 2018
"Scott, it sounds like it may be a species of leaf miner. Removing affected leaves as you have done should help keep it under control. You could also try covering the plants with fine netting to prevent the egg-laying adults from reaching the plants. Leaf miners don't always cause significant damage, but if there are a lot they may reduce the plant's yields."
Ann Marie Hendry on Tuesday 19 June 2018
"Keith, that's interesting - I've noticed far fewer cabbage whites this year too. It could be that there are more still to come though!"
Ann Marie Hendry on Tuesday 19 June 2018
"I have just come to the top of the waiting list and taken over an allotment. The previous tenant scattered nasturtium seeds in what is now my potato plot. I don't care because the leaves cut out the light but I've noticed visits from cabbage whites, confirming what you said. I've also noticed that my pak choi has been stripped by slugs when a row of swiss chard alongside is untouched. "
Robin Wynn on Friday 22 June 2018
"Hi Robin. Keep any cabbage family plants covered with netting, and the butterflies should seek out the nasturtiums instead and not try too hard to get at your brassicas. Pak choi does seem to be a favourite with slugs! Growing it in containers can help."
Ann Marie Hendry on Saturday 23 June 2018
"Following on from above comment re Cabbage Whites. Yesterday I saw one and this is the first time since mid May. Beware, they are on the way presumably."
Keith Boden on Monday 25 June 2018
"reading through your comments and useful advice, I am in the east of Scotland. and it looks like we have all the missing cabbage whiles at least 6 today . Happily munching and laying in all my nasturtiums. H. Dempster "
H. Dempster on Saturday 14 July 2018
"No you haven't Mr D. Ever since 1st July there have been an increasing number here in Sth Staffs. About 5 at a time. Cabbages are covered OK, but now they are laying eggs on my Sprouts. Have been tearing them off the leaves."
Keith Boden on Saturday 14 July 2018
"Greeting! i am growing "all year round cauli" in my raised bed. My first attempt! These are phenomenally large and have caterpillars on them. i did not put the netting. I am resigned to loose this crop but very keen to learn what do in early autumn/winter so that they don't destroy the plant next year. I believe they reside in soil over the winter ? (i might have got it wrong!) . any advice in greatly appreciated. I live in Inverness, UK thanks SB "
Sudhir Borgaonkar on Friday 27 July 2018
"Greetings Sudhir! You won't necessarily lose the cauliflowers - just pick off any caterpillars you see. They don't overwinter in the soil, but in the autumn and winter you might see pupae on sheds, fences or other vertical surfaces. The best way to avoid them reaching your cauilflowers is to cover the plants with netting as soon as you put them in the ground."
Ann Marie Hendry on Friday 27 July 2018
"Thank you, Ann Marie The pupae in autumn/winter -on sheds/fences/ vertical surfaces of the raised beds- will they not attack the cauliflowers in the next summer? ( not understood the life cycle of these caterpillars hence the problem....) that was a big mistake not to cover the plants as soon as i planted them! pl let me know about the life cycle or guide me to a info source about their life cycle. What i cant get from anywhere is - what happens after winter? do they fly away a butterflies or reside in the same soil to attack the crop next year and perpetually , ever after... thanks Sudhir"
Sudhir Borgaonkar on Friday 27 July 2018
"Hi Sudhir. The butterflies lay their eggs on the leaves of brassica plants. The eggs hatch into caterpillars. After a few weeks they pupate, either remaining on the plant they've been feeding on, or in other sheltered locations. A few weeks later (or in spring, if it was a late starter), they will emerge as butterflies, fly around, mate, and lay eggs on brassica plants. It's important to pick off caterpillars (or pupae) as you see them to interrupt this life cycle, and to keep brassica plants netted to prevent the butterflies from laying eggs on the leaves. "
Ann Marie Hendry on Friday 27 July 2018
"Thank you, Ann Marie Best wishes Sudhir"
Sudhir Borgaonkar on Friday 27 July 2018

Add a Comment

Add your own thoughts on the subject of this article:
(If you have difficulty using this form, please use our Contact Form to send us your comment, along with the title of this article.)

 
   
(We won't display this on the website or use it for marketing)



Captcha


(Please enter the code above to help prevent spam on this article)



By clicking 'Add Comment' you agree to our Terms and Conditions