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4547 Views 4 Replies Last post: Oct 23, 2010 7:59 PM by foxylad RSS
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Oct 20, 2010 8:26 PM

A sawfly larva for id please !

Hello all,this is a request for help with a sawfly larva that I have been finding in  small numbers on Meadow vetchling in a bog over the last 2 yrs.It is about 30mm long ,grey with a black head and a thin white line down its back,the underside is white.It is only found singularly on scattered plants,it feeds only on the vetchling though I have found it basking on clover and small blackthorn,never feeding.The bigger it it the more it looks like the vetchlings seedpod.Hope this is in right thread and you can help.Found between late August and October.

P.S this is from Ireand.

20/10/10 Ihave kept larva in pot to id adult if it pupates,today I noticed it had changed colour to a more greenish base colour with pattern on back.I am uploading 1 more picture.

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    Oct 21, 2010 9:12 AM (in response to foxylad)
    Re: A sawfly larva for id please !

    I see that you have been looking for an answer on this last year – contenders then were the scarce Aprosthema melanura (I can’t find any images of the larva of this species for love nor money) or Pristiphora fulvipes (more usually a Salix feeding species).

     

    Have you tried the ‘sawfly botherers’ on the Sawfly Recording Scheme e-group I wonder?

     

    If not I will post a link there and see if we can get this mystery solved – I must admit to being more than intrigued myself, more so now it has moulted into something different looking altogether.

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      • Currently Being Moderated
        Oct 23, 2010 9:19 AM (in response to foxylad)
        Re: A sawfly larva for id please !

        Hi foxylad,

         

        Good news I posted a link on the sawfly group and they have not let us down. John Greason one of the leading UK sawfly specialists has provided the following observation/comments (and I provide the link to images and info on the adult):

         

        These images show a larva of Tenthredo notha, it is a dead match for some similar images taken in the Czech Rep. by Jan Macek. The earlier pictures with the black upperside and the intermittent white line down the back are at the feeding stage. The final picture shows the eonymph stage assumed when feeding is finished and is the stage it will remain in over the winter, buried in the litter or earth below the foodplant. Pupation will take place next spring a week or two prior to emergence.

         

        In the literature I can find references to three other vetches but not Lathyrus pratensis. The plants mentioned in Lacourt (1999) are Trifolium repens, P. pratense and Vicia cracca.

         

        It would be best to keep the specimen outside in a sheltered place to experience the natural temperatures and humidity of winter. Just keep the rain off.

         

        Images of adult: http://www.commanster.eu/commanster/Insects/Bees/SpBees/Tenthredo.notha.html

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