Cocoon

08 Saturday Jul 2023

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Aproceros leucopoda, Elm zigzag sawfly, Elm zigzag sawfly cocoon, insect cocoon, leaf damage by Elm zigzag sawfly larvae, Wych elm, Wych elm leaves

At this time of year, whenever I spot a Wych elm tree, I spend a bit of time staring at the leaves. I look for two things in particular: the first is to see if I can spot any White-letter hairstreak butterflies flitting around, usually at the top of the tree but also lower down; and the second is to see if anything has been nibbling at the leaves. My searching paid off last week when I spotted the distinctive signs of leaf damage caused by the larvae of the Elm zigzag sawfly (Aproceros leucopoda), not necessarily a good thing as this is an invasive species, which I found new to Wales in October 2021 (Zorro comes to Wales) and which is now slowly spreading westwards. But, more interestingly in this particular case, I found one of the cocoons the larvae pupate in, a very delicate, woven-silk structure (you can see an occupied cocoon on the Forest Research website). This one was empty so I guess that’s one more adult sawfly helping to spread the species further.

230708 elm zigzag sawfly cocoon

The return of Zorro

14 Saturday May 2022

Posted by sconzani in insects, leaves, trees

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Aproceros leucopoda, Elm zigzag sawfly, sawfly larvae, sawfly on Wych elm, Wych elm

If you’ve been following along here for a while, you might remember last year’s ‘first for Wales’ find, the distinctive marks on leaves of Wych elm trees of the Elm zigzag sawfly (Aproceros leucopoda) (Zorro comes to Wales, October 2021). For the past couple of weeks I’ve been monitoring the trees where I first saw those marks and, yesterday, found them again, with the larvae that create them in situ, happily munching away on the elm leaves. In fact, following a good look around the area, I found larvae on six Wych elm trees (and there were other trees I couldn’t access), and then found a single larva on a Wych elm at Cosmeston, perhaps half a mile away. It will be interesting to see how quickly these creatures spread through the local landscape.

220514 elm zigzag sawfly larvae

Zorro comes to Wales

21 Thursday Oct 2021

Posted by sconzani in insects, leaves, trees

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Aproceros leucopoda, British sawflies, Elm zigzag sawfly, sawfly feeding marks on elm leaves, sawfly on Wych elm

‘Yes it’s definitely Zorro’, confirmed Andy, a county sawfly recorder, when he took a look at these photos on Twitter on Tuesday. Andy was not, of course, referring to the legendary fictional character of book, television series and movie, but to the creature that created, in the leaves of Wych elm, these characteristic feeding marks that resemble the trademark ‘Z’ signature the big screen version of Zorro left at the scene of his adventures.

211021 elm zigzag sawfly (1)

Zorro, in this case, is the Elm zigzag sawfly (Aproceros leucopoda) and my photos are the first records for this species in Wales. The find is a double-edged sword (see what I did there?), as this sawfly is considered an invasive species, though I am assured by those who have been following its spread in England that the damage it does is not as considerable as first feared. I hope to spot the larvae that do this damage sometime next year.