Friday, July 16, 2010

Gooseberry sawfly


A few weeks ago, when I photographed these little hymenopterans - each about five millimetres long - I knew the pattern of events that was about to unfold in our garden.


These are gooseberry sawflies that were busy mating and looking for somewhere to lay their eggs.


 They're attractive little insects, but when they hatch their larvae....
  

... have a phenomenal ability to defoliate gooseberry bushes. These six bare leaf stalks were fine healthy leaves the day before this photo was taken...... 


 ....before the gooseberry sawfly larvae got to work.


Last year I posted on the Solomon's seal sawflies that breed in the garden and lay their eggs on their host plant in early May. They're back this year and here are their larvae at work. They are highly organised defoliators, perhaps sticking together for mutual safety. When they are tiny they just strip layers of tissue from the understide of leaves and so pass unnoticed, but when they get to this size you can almost see the leaves disappear as you watch.


 This is insect teamwork in action.

I could, I suppose, follow the advice in gardening books and take drastic measures to wipe them out but the Solomon's seal sawfly population has been established in the garden for about a decade or so and the larvae only make serious inroads into the plants long after they have finished flowering. They haven't prevented the Solomon's seal from thriving and spreading a little further every year. As for the gooseberry sawfly, well that only gets into its stride once the fruits are well on the way to ripening - and there are only so many gooseberries that it's wise for a human to eat anyway. And as the old saying goes, 'it's an ill wind that blows nobody any good' - the sawfly larvae provide a food source for many of the garden birds.

8 comments:

  1. Phil,
    Our Solomon's Seal plants are now just bare stems, but as you say they will be as good as new next spring
    Dick

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  2. Well, I suppose everything has its part to play in the Great Scheme.

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  3. And that shows just how nature maintains the perfect balance.
    A shame the human race came along and spoilt it.

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  4. I like your perspective Phil and glad that you take no notice of the gardening books. :D What a lovely photo of the gooseberry sawfly larvae!

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  5. Hi Dick, they do seem to be very resilient plants. Once they've stored plenty of starch in their rhizomes, they seem to be able to withstand a lot of leaf damage..

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  6. I'm sure you're right lotusleaf - all part of the food chain..

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  7. Hi Keith, blue tits and great tits seem to be very really useful allies it keeping numbers of larvae like this in check..

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  8. Hi Lesley, most of the time I just let nature take its course... which seems to work pretty well

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