Grubs found in a bag of soil - identification, please

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JTh

  • Hero Member
Grubs found in a bag of soil - identification, please
« on: October 09, 2016, 06:40:06 PM »
I planted a tree today (a persimmon), and mixed the rather poor soil we have with soil bought in a large bag this summer. I was surprised when I saw the first big larvae and found that it came with the soil in the bag, then I found a lot more, I believe around 50 in about a 1/3 of the bag. They were quite large, the largest ones around 5 cm long, around 1 cm in diameter, greyish with a paler underside, slightly hairy. They moved in a very strange way, creeping on their backs. The bag had been opened this summer, but the larvae were spread around in the whole bag and I believe they were there when I bought the soil.

I would very much like to know if anybody could identify these.


_A093689 What did I find in a bag of soil?.jpg
by Jorun Tharaldsen, on Flickr

I got one photo of the underside of  a larva:

_A093688 Unidentified grub.jpg
by Jorun Tharaldsen, on Flickr

Retired veterinary surgeon by training with a PhD in parasitology,  but worked as a virologist since 1992.
Member of the MGS  since 2004. Gardening in Oslo and to a limited extent in Halkidiki, Greece.

Joanna Savage

  • Sr. Member
Re: Grubs found in a bag of soil - identification, please
« Reply #1 on: October 10, 2016, 04:31:05 AM »
Jorun, I don't know what this grub is or whether it is harmful to plants. However, in earlier days when I was preparing pots sometimes  I did not make the drainage holes large enough and the contents of the pot soon became waterlogged, even flooded. Grubs like those you show would come  to the surface and  die. And that was a bought-in potting mix.

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JTh

  • Hero Member
Re: Grubs found in a bag of soil - identification, please
« Reply #2 on: October 10, 2016, 08:04:36 AM »
Joanna, I'm not very concerned about these, I'm just curious and want to know what they are. They are probably  beetle larvae, but they were exceptionally big. I just picked them out and threw them away, I don't think they are necessarily harmful.
Retired veterinary surgeon by training with a PhD in parasitology,  but worked as a virologist since 1992.
Member of the MGS  since 2004. Gardening in Oslo and to a limited extent in Halkidiki, Greece.

JayB

  • Jr. Member
Re: Grubs found in a bag of soil - identification, please
« Reply #3 on: October 10, 2016, 12:54:49 PM »
Could they be Chafer grubs which are the larvae of the Cockchafer?
G'day from an Aussie in Spain. Currently attempting a total garden overhaul.

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JTh

  • Hero Member
Re: Grubs found in a bag of soil - identification, please
« Reply #4 on: October 10, 2016, 01:23:27 PM »
Yes, larvae of the genus Melolontha, cockchafer, is definitely a possibility, the development is very slow and the larvae can grow to a size of about 4–5 cm. I am glad I picked them before adding the soil to the newly-planted tree.
Retired veterinary surgeon by training with a PhD in parasitology,  but worked as a virologist since 1992.
Member of the MGS  since 2004. Gardening in Oslo and to a limited extent in Halkidiki, Greece.

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Fleur Pavlidis

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Re: Grubs found in a bag of soil - identification, please
« Reply #5 on: October 11, 2016, 01:16:23 PM »
If you search for Chafer on the compost page of the MGS website [urlhttp://www.mediterraneangardensociety.org/compost.html][/url] you'll find that they are useful in compost making. In a discussion about the larvae in TMG a long time ago there were many suggestions how to kill them including getting a hen, but I seem to recall that the last contributor was convinced that they are harmless in the garden. I wouldn't want to put them in a planting hole, though.
MGS member, Greece. I garden in Attica, Greece and Mt Goulinas (450m) Central Greece

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JTh

  • Hero Member
Re: Grubs found in a bag of soil - identification, please
« Reply #6 on: October 11, 2016, 08:26:25 PM »
Thank you, Fleur, lot's of useful information there. I think it is safer not to put them in the planting, as well, I read that cockchafer larva: 'Feeds on fresh roots, does great damage'
Retired veterinary surgeon by training with a PhD in parasitology,  but worked as a virologist since 1992.
Member of the MGS  since 2004. Gardening in Oslo and to a limited extent in Halkidiki, Greece.