New Zealand Flatworms

New Zealand Flatworms feed on our earthworms reducing the condition of the soil. They were indeed a worry to me when I first discovered them in my garden over 10 years ago. Gardening magazines at the time showed pictures of devastated gardens with plants dying or dead as a result of the absense of earthworms where flatworms were reported.

The Flatworm doesn’t destroy the plant only the earthworm which enriches the condition of the soil so the plant grows well. All is not lost if you have just discovered the flatworm in your garden – perhaps under the base of a pot as I did. Gardens can survive with, and after, flatworms as I myself can confirm. However if you have flatworms you must take extra care to prevent them spreading further. To see a New Zealand Flatworm and its egg click here .

BBC Gardeners’ World Magazine, at the time of my discovery of flatworms, had just issued an article on the New Zealand Flatworm with some lovely (not) colour photographs. How fortunate that was for me. It had a brief description of how it could change its shape making itself so thin that even if you tied a knot in a bag there was still a chance it could escape – this was very accurate as I have witnessed! The article also showed a map of the UK with locations where they had, at that time, been reported. It also asked for new sightings to be reported so data could be compiled and as they were only starting to appear in my area I felt a sense of obligation to report mine.

The Scottish Crop Research Institute, in Invergowrie, was where I reported my sighting. I phoned the contact given, Dr Brian Boag, who was conducting research on them at the time. I can clearly remember asking if I was the first to report from my town and feeling the horror that – I was! He told me how to trap and destroy them and also to look out for eggs (like small oval blackcurrants) and destroy them too. I kept a jar, with screw top lid, at my back door with very salty water in it – behind a plant pot so I didn’t need to look at it!

Carrier bags filled with soil, were the traps I laid, on bare pieces of soil where possible. These weren’t the most attractive addition to my garden as you can imagine! It did work though. I found the carrier bags needed to be of good quality to last out in the rain etc. I do remember going into my nearest Laura Ashley store asking if I could buy some of their dark green carrier bags (a bit more camouflaged in the garden when turned inside out) but I couldn’t persuade them at all!

Coiled-up flatworms could be found under the carrier bags during my daily morning check – I could collect up to five. It did seem if I was lucky in one area I could put two bags there and be twice as lucky! The flatworm did seem to return to the same area once it was found there. I did also notice that the soil was warm as well as damp which must have been ideal conditions for the flatworm when I was so successful with my traps. I can recall gingering lifting them up with my garden trowel and trying to shake them off into my jar. It’s really a good job you can’t see my face squirming at the thought of it. Within two days of being in the jar they turned milky-ish as their own poisonous enzyme, that destroyed the earthworm, destroyed it. I am now absolutely cringing at the thought of them decomposing now. It’s coming back to me now – the awful smell inside the jar when I opened it.

I took the brave step of telling my neighbours – not a popular move at the time! The reality was that although I had identified Flatworms I hadn’t necessarily been the one who had brought them to my garden. Knowledge is power, so I thought, the more people that were aware of the problem the higher the chance of stopping them spread. I also took the step of rinsing the roots clean on any plants that I gave away to friends and family. I did my best to stop Flatworms spreading but like a needle in a haystack I had absolutely no chance of trapping them all.

Earthworms are scarce, in my garden, and if I ever find one when digging I feel delighted to see them again – hey I know that sounds sad but it is true. Pre-flatworms I would be uninterested in the seemingly insignificant earthworm – but gosh does do it not do an important job with our soil! My soil only gets aerated when I dig or hoe it and if I don’t a type of moss will grow on the surface of my soil. So, a little work is required to keep the New Zealand Flatworm at bay and the soil in order – but looking round the garden at my plants it is undoubtedly worth it.

For further information on the New Zealand Flatworm go to:

5 thoughts on “New Zealand Flatworms

  1. I have New Zealand flatworms in my garden, I have just been collecting them and squashing them in plastic bags. Have you still got them and are the earthworms now coming back. I am sick at the thought of them out there killing the earth worms. What about my compost bins, they are full of worms, will the NZFs get in there?

  2. Hi there, Anon

    I am sorry to hear that you have New Zealand Flatworms in your garden 🙁

    As I have said in my post above you must destroy them by putting them in a jar of salted water – squishing them may not kill them.

    The last time I have seen Flatworms in my garden was at the end of May – you can see a photo in my post blog.shirlsgardenwatch.co.uk/2007/05/still-with-us.html .

    I occasionally find earthworms but am sorry to tell you I do not have many at all. I often have a kind of moss growing over the surface of the soil as the earthworms have been unable to aerate it – I tend to use a hand fork to do this myself 😀

    I cannot say for sure if the flatworms would go looking in compost bins for earthworms but what I will say is that they are found in damp places. Therefore, I would think that the heat in a compost heap would not be to their liking.

    I can completely understand how you are feeling about discovering them in your garden and that they are killing your earthworms. All I can say to help is trap them, kill them and keep your soil aerated and your plants will be fine. Good luck 🙂

  3. Hi Shirl
    Since I was last here I have been collecting the NFWs every day and at first I got 2 or 3 always in the same places under heavy pot. I put out more traps nearby and now I seem to get 5 or 6. I put them in the jar of salty water. I never see eggs, but come across tiny ones which have just hatched out as well as huge ones. How many more are out there? My compost bins are cold, I emptied one out recently and it was still full of worms which was good. Thanks for advice about jar of salted water, its a good deal better than trying to squash them.

    Your photos of garden and birds are great.

  4. Hi again, Ann 🙂

    Thanks for the update on the flatworms in your garden. You ask how many more – that I couldn’t guess. All I can say is that the more you collect the quicker you are stopping the eggs being laid! I would continue with your traps but perhaps think about widening the area out from where you found them first by adding more traps.

    I have been thinking since your comment if I found any during the winter months. I cannot remember now. The ground will soon be getting hard with frost so perhaps the flatworms will go deeper into the soil, I’d try and catch as many as you can now. Good luck. Salted water is the only sure way to kill them.

    Thank-you – I really enjoy taking photos in my garden 😀

  5. Ewww! I have found three of these horrid worms today! I noticed a year or so back that I had less and less earthworms. Maybe I shall start a small wormery. First I need to catch more flatworms!

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