• Question: Why is it toxic?

    Asked by ty11 to Oak Apple Gallwasp, Giant Hogweed on 21 Nov 2017.
    • Photo: Giant Hogweed

      Giant Hogweed answered on 21 Nov 2017:

      Hello, thanks for your question. I’m toxic because my sap has a toxins which cause photodermatitis, making the skin sensitive to sunlight and other sources of ultraviolet light. It can therefore cause skin to blister or become pigmented, causing long-lasting scars.

      Simply brushing against or touching the plant is enough to release the sap, and can cause serious burns within around 24 hours. If the sap comes into contact with the eyes, it can cause temporary or permanent blindness.

      Hope this answers your question, and keep asking great questions like this!

    • Photo: Oak Apple Gallwasp

      Oak Apple Gallwasp answered on 2 Dec 2017:

      Gallwasps aren’t toxic to us, and maybe not to anything. They have a sting and a venom gland, but rather than using it to kill prey or defend a nest (as the Asian hornet does), they use their venom to influence how a plant grows, and to make a gall. So, their venom doesn’t contain poisons in the usual sense, but instead a load of other compounds that influence plant development somehow.

      To explain a little further – when a mother gall wasp lays her egg on a plant, something weird happens: the plant cells around the egg dissolve to make a space into which the egg moves (moving eggs? weird!). Other plant cells around this space change their form, and take the first steps into becoming a gall. The cells grow and multiply and change, forming the gall tissues that will feed and protect the developing gall wasp larva. This usually doesn’t hurt the plant, as far as we can tell, though there are some exceptions (see my profile!).

      So this all starts with a gall wasp sting and egg laying.

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