Saturday, 8 February 2014

Larva on Broom

On a brief visit, yesterday afternoon, to a favourite site near Abernant, I took a close look at one of the three plants of common broom growing there and found lots of dark grey, almost black mines in the bark of the stems, plus abundant feeding damage to the green, fleshy wings that run along the bark. While looking at these, I noticed something tiny and yellow protruding from one of the stems, at the very top of one of the mines, which on closer inspection turned out to be a larva. I examined it with a hand lens and it seemed to be dead and damaged. I decided to leave it there and collect it on my way back to the car, but typically for me, I forgot all about it and went back by a different route.
This lunchtime, I went back for it and it was still there, in the same position, so I took it, along with the section of shoot it protruded from.
At home, I got it under the stereo microscope and  was amazed to see it was still alive, and swaying about very slightly and very, very slowly. I decided that either it was parasitised, had suffered some sort of mechanical injury or had somehow become trapped, so I carefully picked away the plant tissue surrounding it so I could inspect the whole of it and photograph it.

I can't decide whether it is Leucoptera spartifoliella or Trifurcula immundella, but based on the larval descriptions in Heath and Emmet, plus Dave's photos of the larva of L. spartifoliella on UK Moths, I am inclined to T. immundella and would welcome suggestions, please.


  1. Johansson et al (Fauna Entomologic Scandinavica describes the colour of Trifurcula immundella as "bright amber yellow", which certainly fits your larve. I'd say you are quite right.

  2. Also worth having a look at Tony Davis's blog post:

    Which also suggests immundella. You can also look for the egg shell which would add extra evidence.

    Would this be new for VC41 Dave? I found them in Wentwood Forest, VC35, in the autumn, but couldn't find any mines at Forest Fawr/Castell Coch (only larvae of Agonopterix assimilella, which were common).


  3. I thought there was a record, but the only VC41 record we had was an unverifiable record from an unknown source, and therefore was put in the appendix. This will be the first confirmed record.

  4. Thank you both. I've examined the small piece of shoot I collected with the larva and can see nothing that resembles the remains of an egg, so I will try and visit the site tomorrow morning, before work, to check the rest of the plant. Are the eggs visible to the naked eye or will I need to use a hand lens? I presume I'd be looking for something whitish and speaking of white, the showers are now falling as icy sleet and are forecast to turn to snow overnight. If so, I hope the snow doesn't settle to any degree, as it would make getting up to the site tricky if not impossible. Anyway, watch this space.

  5. The eggshells are shiny and blackish - I'll email you a photo.

  6. Nice find Mark - it's good to see something interesting turning up in this awful weather!

  7. Thanks Adam, but as usual with me, it was more by luck than judgement. I was actually looking in vain for rusts.