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Increasing importance of common white butterflies in pollination

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Hi

This is a bit off piste re bumble bees but I was thinking about this the other day and just wondered what other members thought.

My garden is dominated when it comes to bees by bumble bees, I very very rarely see a honey bee, assuming the garden is out of range for any local hives.

However looking out recently over the garden it occurred to me that there is rarely a moment during the day ( at least a warm sunny day )  when butterflies, and particularly small and large whites, are not in the garden. I wondered just how important these two species are becoming as pollinators for our flowers and crops in gardens, allotments and farms, keeping in mind the decline of our bees. They have a reputation amongst gardeners as pests, but with the decline of honey bees and bumble bees, are these two “pest” species actually increasingly important as pollinators and should we be looking at them from a totally different angle. Does the good outweigh the bad.

I did a very rough estimation in my own garden and came to a very unscientific conclusion that butterflies in my garden probably nectar feed ( and presumably pollinate ) about 10% compared to the bumble bees in terms of number of visits. If that is anywhere near accurate and the butterflies are doing a similar job in pollination then it’s important if you then link it to commercial value ( which of course you’d have to to compare to their destructive value in crop loss) . Has anyone done any comparative studies and if not perhaps it’s time we did, if only to know the results?

I’m interested to know what other forum members think, perhaps all this has been done and known but I haven’t been able to find anything online and haven’t yet contacted the butterfly conservation sites.

David

     
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These butterflies are a pest.  Probably Cabbage Whites.  They lay their eggs on any brassicas and within a few days they are covered with caterpillars.  I lost over 60 cabbage plants, broccoli plants and nearly my Brussels Sprouts as well to these horrors.  The caterpillars stripped the plants bare in a very short space of time.  I wept when I saw the damage.  The hard work I’d put in digging the ground, sowing the seeds in the greenhouse then planting them out when they were big enough was soul destroying.

I didn’t touch my back garden or my greenhouse for about 6 years and it’s only this year I’ve started again although I’ve only planted broad beans and peas this time (bees have done a great job of pollinating them).

I won’t use pesticides so next year when I plant my cabbage etc., I’ll be using nets to keep the Cabbage Whites (and other pests) off my plants.

     
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Yes I know they can be a pest to gardeners, especially if you allow them to access the plants. Try growing nasturtiums as a companion plant , the whites love them to lay eggs so they might divert a few

Anyway, every species has a commercial value if it can be worked out, what I’m trying to find out is is if anyone has done the maths. Does the damage to crops and gardens etc exceed the pollination value which must be significant? And with the decline of bees as pollinators should we not be encouraging white butterflies rather than condemning them?

David

     
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Davidbirding - 09 August 2013 06:14 PM

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Yes I know they can be a pest to gardeners, especially if you allow them to access the plants. Try growing nasturtiums as a companion plant , the whites love them to lay eggs so they might divert a few

Anyway, every species has a commercial value if it can be worked out, what I’m trying to find out is is if anyone has done the maths. Does the damage to crops and gardens etc exceed the pollination value which must be significant? And with the decline of bees as pollinators should we not be encouraging white butterflies rather than condemning them?

David

My opinion only but the damage these things cause outweighs any potential benefit.  I worked hard raising the plants from seed then to see them stripped bare literally overnight, I’m not joking I did weep.  I’m not particularly well off and these plants would have given me enough veg to keep us going for months.  There was also the cost of buying the seeds, the many hours I spent in the greenhouse and garden tending them, running the greenhouse heater when it was cold etc. and the hard work digging the ground.  We have heavy clay soil here and it’s a nightmare to dig.

A hard lesson learned - use nets which I did this year on my broad beans which kept other pests away until the plants were more mature (caterpillars not a problem with beans).  Took the nets off prior to them flowering so my resident bumblebees could do their job.

For the butterflies I always leave a large patch of nettles at the far end of the garden beside the compost heap and there is a Buddleja bush which overhangs my garden from next door but Cabbage Whites being Cabbage Whites prefer, well, cabbages (brassicas in general).

Next year I should have my raised beds up and running so will see what the best companion plants are (do some of that already - you won’t find any midges near lavender or greenfly where there’s Marigolds).  I like Nasturtium as they brighten up any garden so will sow some and see if the Whites go for them instead.

For the record, even though I think they’re a pest, I won’t kill or harm them.

I will kill slugs though as I’ve been having a major problem with them this year.  Won’t use slug pellets as they can be harmful to beneficial insects and pets so have been using salt which works quite well.  The only problem with that is if it rains.