Saturday 27 July 2013

Invasion of the "Cabbage Whites"

Until recently, there have been very few butterflies around this year, but with the advent of really hot weather one particular type has come out in swarms - the Small White, or Pieris Rapae, aka "Cabbage White". At times I have seen 10 or 12 simultaneously - which is a lot for my little garden. In fact, too many!


This butterfly is a real menace in the vegetable garden. It lays multitudes of eggs on the undersides of vegetable leaves - usually those of Brassicas - and when these hatch they turn into voracious caterpillars which can devour a cabbage plant in a very short space of time, leaving it with that characteristic "lacy" look.

Here is one Cabbage White caught in the act of laying eggs:-


And here is a cluster of its eggs. Fortunately, being bright yellow, they are easy to spot. I can't imagine why the eggs are that colour. Surely it would have been better for the butterfly if they were a more unobtrusive colour?


Right now the Cabbage Whites don't have a lot of choice if they want to lay eggs on brassicas in Mark's Veg Plot. I have only four Brussels Sprout plants for them to choose from (as long as they don't notice the two trays of tiny PSB and Cavolo Nero seedlings!). This means that it is easy enough for me to "patrol the brassicas" and remove the eggs. I simply rub them off with my fingers. I did consider putting a net over the plants again (I had them covered when they were small), but I think that I'll manage to control the situation OK without it.



So far I seem to be winning the battle because I have only seen a few caterpillars, despite having removed dozens of clusters of eggs. I did resort to spraying the growing tips of the plants with a proprietary bug-killer because these are the most important parts, but it is not a good idea to spray the whole of the (very large) Brussels Sprout plants if you can avoid it.

On second thoughts, I have remembered that I still have some turnips left, and they are brassicas too. Better check them as well... Cabbage White = Pieris Rapae; Turnip = Brassica Rapa!

Cabbage White on a Turnip leaf

11 comments:

  1. We have had hoards of butterflies on our buddelias today, peacocks, commas, tortoisehell, gatekeepers and a skipper but there were whites about too.

    I think those eggs are from the large white butterfly Pieris brassicae as the small white lays single eggs. Unfortunately the large white is more destructive down to more caterpillars hatching in one place.

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  2. Thanks for the info, Sue. I did today see some of the larger Whites, and on close inspection I also saw lots of single eggs - they are a sort of greyish-white colour, so much less obvious than the yellow ones from the Large White! The single eggs are so much harder to spot!

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    1. I suppose the larger whites lay more as they are more obvious and so liable to predation.

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  3. Well, Mark, what are you going to do? Do you try to eradicate the butterflies or remove and destroy the eggs or what? I have not seen those here on my cabbages, but I have cabbage in the winter and there are less butterflies than in summer. I don't think I have seen the white butterflies.

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  4. I have the same issues here Mark, twice daily patrols are seeing me through. The amount of eggs I have rubbed off & the odd caterpillar squashed means there will be several thousand less of these butterflies next year.

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  5. We mostly get the ones that lay the white eggs here. I try and rub my hands over the underside of all the leaves of my brassicas every day or two and that controls the problem. Here they aren't too much of an issue in summer but are worst in Autumn when the brassicas are moving from seedling stage to larger plant stage.

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  6. We mostly get the ones that lay the white eggs here. I try and rub my hands over the underside of all the leaves of my brassicas every day or two and that controls the problem. Here they aren't too much of an issue in summer but are worst in Autumn when the brassicas are moving from seedling stage to larger plant stage.

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  7. We get those as well, a badminton racket makes for good if somewhat intoxicated appearing butterfly control.

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  8. Good luck with those. They I way I never grow any brassica except under cover. They will eat everything down otherwise.

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  9. We've had clouds of white butterflies wheeling about the garden for weeks too. The single eggs of the small white hatch into green caterpillars which are much harder to see on the leaves than the black and white ones of the large white; the small white obviously favours sneak attacks over the large white's attack-by-numbers!
    I've been blasting/rubbing/picking eggs and caterpillars off the few unprotected kales in our veg patch, as well as some of the plants beneath our mesh cages. There are a couple of holes in the mesh, and those butterflies are crafty - though the mesh does keep the majority off, so a weekly check on the plants suffices. Such pests though.

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  10. I always think those little white butterflies mean trouble. I've also been finding some of their eggs under the leaves of lettuce and chard. Suppose its a good time of year to do regular inspections.

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