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Hornbeam (and other woody plants)

Hi, I seem to have a lot of what I would call slate beetle insect attaching permanently to stems and on lifting the insect there is evidence of a soft larvae which borrows up  the stems causing damage and even limbs dropping. How do I treat these? Do I need to be worried about that? What is the best insecticide to use? I just don’t know what I’m dealing with. I’ve not seen this insect in the area before but it seems to be very heavy. I sore a reference to’mummy wasp’ which were numerous with no bees this year. There was mass brown husks attached to the plants at the end of spring. PLEASE HELP 


  • FairygirlFairygirl Posts: 54,782
    Do you mean scale insect?
    I'm struggling to understand some of your post. Do you have a photo? That will help with advice.
    If you can add more info too - location, general climate etc, that will also help  :)
    It's a place where beautiful isn't enough of a word....

    I live in west central Scotland - not where that photo is...
  • LynLyn Posts: 23,190
    Fairygirl said:
    Do you mean scale insect?

    Woodlice to us @Fairygirl . Maybe they’re different in another country. 
    Gardening on the wild, windy west side of Dartmoor. 

  • GardenerSuzeGardenerSuze Posts: 5,620
    edited December 2022
    Mummy Wasps or Parasitic Wasps are good to have in the garden.
    Slate Beetles or Woodlice like dead wood they do move about. I also think you might have scale insects which fix to the branches and they can overwinter. You could try brushing the stems squashing them is another idea. 
    I don't think this problem is affecting bees. Perhaps next year you could add some more plants that bees love.
     Retired Gardener, new build garden, clay soil, South Notts.

    The more I garden the less I know but the more pleasure I get from it. Monty Don 
  • FairygirlFairygirl Posts: 54,782
    That crossed my mind @Lyn [slaters here] but it was the description of them attaching to stems that puzzled me  :)
    It's a place where beautiful isn't enough of a word....

    I live in west central Scotland - not where that photo is...
  • thanks guys for your responses it’s really given me some insight into what is happening. However, if I expose deeper into the stem of the plant there seems to be some sort of Larvae  which eats its way up to the stem. Do you know what this might be guys? Thanks for your insights and advice. It’s really helpful. 
  • A clear pic to show these would give a positive /accurate answer.
    Do please add a pic to this thread.
    Maybe you have a friend to help you to do this if you haven't got a smart phone or camera.
    Take lots of pics and only post the clearest one.
    Perthshire. SCOTLAND .
  • Silver surferSilver surfer Posts: 4,709
    edited December 2022
    That is serious.
    These trees/shrubs appear to be dead.
    Could it be that something has killed phytophora.

    Then bark has peeled away leaving tree completely dead.
    Bugs, worms etc are just eating into the already dead wood.

    See what others say.
    I recommend removing them all asap and if possible burning everything.
    Please do not put in council green waste.
    Do more may not be able to replant with new woody plants for years.
    Perthshire. SCOTLAND .
  • That worm is just a type of earthworm and not doing any damage. 

    It looks to me as if you have several things going on there … squirrel or deer damage rubbing, shredding and tearing the bark, which will kill the trees. There’s also some wood-boring beetle grubs in there. 

    Sorry to ask for more photos but could we see some of the whole trees please  … it could give us more clues. 

    Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.

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