Eliminate the beetle larvae

Hello, I have been using a composter for about 1 year. For some months, when I turn the compost, I have seen moving in the maturing mass of white "worms" (about 2 cm long) which are the same ones that I happened to find in the pots of suffering or dead plants.
What should I do to eliminate them?
Thank you in advance for the information you can give me.


Hello John, first of all you need to identify the larvae: the beetle ones are characterized by their plump shape, they are white, with the head on brown and in front they have paws. Description and dimensions you make are consistent with this insect.

The beetle (Melolontha melolontha) is a beetle, belonging to the beetle family, as an adult it becomes large and flies little, it does little damage to plants but when it is a larva it is really a disaster to have it in the garden since it feeds on roots and therefore makes the plants suffer a lot. Unfortunately, this insect has a long life cycle and remains a larva for three years, so it is definitely harmful. The adult lays its eggs in the soil, prefers fertile soils and therefore compost is an inviting habitat for him. Once the eggs have hatched, the larva goes deep where it remains during the winter, while after the frosts it re-emerges to feed on our seedlings.

Distinguish cetonia and beetle larvae

Before decreeing that it is a beetle, it is necessary to pay attention to the paws: in fact, there are cetonia larvae which are very similar, but do not have developed forelimbs. The cetonia in the larval stage is useful: it chews organic substance digesting it and is harmless for the roots of plants. So before eliminating the larvae, check for the presence of the legs, if there are, it is a beetle and it is an "enemy" of the garden, otherwise we let the young insects take their course.

Eliminate the beetle larvae

But let's get to the point and see how to eliminate the beetle larvae from the garden ...

For prevent the problem first of all, the soil must be turned often, or in Giovanni's case the compost heap. In this way, the beetles finding it soft will avoid depositing eggs. If you also want to keep adult beetles away, you can put a nice bat box, as bats are fond of these beetles.

However, if you have to intervene on an infestation that has already started (as in the case of Giovanni), a more immediate solution is needed. On the larva, the 'neem oil, a very useful biological insecticide, but being a product that acts by contact we cannot think of finding all the beetles in order to eliminate them. Since the larvae are in the soil, something must be used that can disinfect the soil. We specify that by choice we do not use chemical geodisinfestants, therefore we say no in principle to all those products that are not allowed in organic farming. Using a chemical product means killing not only the larvae but also a series of microorganisms that are positive for our crops, impoverishing the land we cultivate.

In the organic garden, a very interesting solution against beetle larvae is the biological struggle, introducing natural antagonists of the beetle so as to make life hard for the larvae. There are for this use of the nematodes which are entoparasites and can be used against the larvae (nematodes Heterorhabditis), alternatively entomopathogenic fungi can also be used but it is much more complicated.

Obviously, if it is a minor infestation it is worthwhile turn the soil or the composter carefully e manually eliminate the larvae, fortunately they are big and white, so they can be identified quite simply.

Other interesting reads:

Matteo Cereda2019-01-28T07: 31: 22 + 01: 00
  1. Marco5 October 2015 at 14:20

    I am writing to you because for 1 year and a half in the meadow underneath a cork plant the beetle larva has settled, last autumn I removed the affected piece of lawn so I worked the soil, removed all the larvae I found and then in spring I sowed the lawn that initially grew well but then once mature the same story began again, the roots are practically eaten and tends to turn yellow and come away easily even with the herb cutter, I would like to have indications of an effective product for the elimination of larvae without having to remove the lawn again and know if they can also damage the cork tree.

    • horticulturist5 October 2015 at 14:22

      I can't be of much use to you as I have no direct experience of large beetle infestations. In the literature we often talk about fighting larvae with nematodes and as I said we also talk about a fungus, but these are methods that I have never experienced in person. I don't think larvae can do any serious damage to a tree.
      I'll stop here, maybe some visitors have direct experience on how to solve your problem.

      • Daisy22 March 2016 at 8:33

        Unfortunately, I'm sorry to contradict you, but this insect can also do serious damage to trees. The beetle larvae that infest my garden and which gardeners have so far failed to eradicate have eaten the roots of every fruit tree I have planted entirely, except citrus, not to mention the flowering bushes. After a few months they begin to yellow and when they are visibly dead they come away without any resistance because they have become stumps without roots.

        • horticulturist22 March 2016 at 16:21

          It is very good to be contradicted if it could serve someone with an experience different from ours. I have always felt only damage to the seedlings, perhaps the fruit trees were still small, however, one more reason to be careful of this insect in the vegetable garden and at this point also the orchard.

  2. Domenico8 June 2016 at 22:45

    I have been cultivating a small vegetable garden for years. From time to time he finds the salad pierced by worms. I found out someone is killed. But others appear. What to do????? The worms are seven or more centimeters long. What do you recommend

    • horticulturist11 June 2016 at 12:49

      It would be clear what worms they are. If they are larvae, baccillus thuringensis is excellent, a biological insecticide harmless to humans.

    • Sal14 June 2016 at 20:24

      Worms six to seven centimeters long !!!! They are earthworms useful to nature

      • horticulturist15 June 2016 at 6:47

        If they are earthworms, they are obviously welcome, the problem is whether they were larvae.

  3. Dalmazio1 July 2016 at 16:34

    If they are earthworms they do not pierce the salad. Earthworms live underground and work the soil and are therefore very useful. A fat, 5-7 cm long worm could be a cabbage maggot.

    • Caesar9 July 2016 at 13:51

      After having removed last year a stump of a beautiful fig whose roots had been devoured by larvae from 3 to 6 cm I thought of planting another one but in the excavation I still found 3 huge larvae. What preventive treatment can I do?

      • horticulturist10 July 2016 at 11:50

        You could try nematodes.

  4. james1 January 2017 at 17:08

    in my garden the green beetles eat fruit, including grapes' and make the plants die.
    what should i do to continue to cultivate my land?

    • Matteo Cereda3 January 2017 at 7:26

      Hi Giacomino, you have to work hard to chase away the beetles. Nematodes are excellent against larvae, on the insect you can manually remove them at dawn (when they are not ready to fly) or try making a trap with a sugar solution.

  5. Maurizio flax13 February 2017 at 14:40

    they made a grapefruit, an strawberry tree, a mango die from me and now they have also taken an orange
    in the strawberry tree, uprooted days ago, the root was now non-existent

    • Matteo Cereda13 February 2017 at 14:52

      Amazing how voracious these insects can be.

  6. Alberto16 March 2017 at 19:45

    I confirm the voracity of these insects. In the summer of 2016, I planted 24 strawberry plants in a large self-made pot. I noticed that beetles were turning in the spring ... then during the summer I could see the rootless strawberry plants with my own eyes. The plants came off just pulling them ... I collected dozens of larvae. I have kept some in a jar and am looking for the treatment to eliminate them. I tried calcium cyanamide but they are not dead. I tried the beauveria bassiana, nothing !. Not even the frost of this winter. I will try the neem in the soil ... insecticide harmless to humans ...

    • Matteo Cereda20 March 2017 at 13:20

      Hi Alberto
      Thanks for the contribution! I took the liberty of eliminating the companies mentioned (but leaving the type of intervention carried out because it was very interesting). Unfortunately, there are many companies that use fake comments to promote themselves or to denigrate the competition, so I usually remove all references to corporate brands. I'm afraid that the neem in the ground is too dispersed, it can only work in a small pot, I don't know if it would be very effective in a vegetable garden. You should try the use of nematodes. Let us know how your experiments go.

  7. Alberto23 March 2017 at 18:59

    Of course Matteo understand, no problem. Thanks for the advice, actually in the garden it would be too distracting and the larvae after moving away a little could return. We'll see if I can get the nematodes, otherwise the only valid solution for now would be to remove them manually but only a few are enough to do irreversible damage to a plant cultivated for years ... I'll let you know .... Alberto

  8. Mario31 March 2017 at 8:11

    But weren't the beetles useful for fighting parasites?

    • Matteo Cereda31 March 2017 at 8:19

      No, not at all. Perhaps you confuse them with ladybugs, a very useful insect against parasites.

  9. Roby16 April 2017 at 20:24

    In autumn, I release them in the vegetable garden and free it from snails, weed larvae and, moreover, fertilize it

  10. Bruno18 April 2017 at 8:15

    where can you buy nematodes to fight beetle larvae?

    • Matteo Cereda19 April 2017 at 6:54

      Hi Bruno, I've never tried it directly, so I don't know how to direct you to a secure contact. If you google "nematodes against white worms" you will surely find some products.

  11. Bruno18 April 2017 at 8:16

    in the stores I contact they only have chemicals that I don't want to use.

  12. james14 December 2017 at 17:42

    I implemented the various advice I received but unfortunately the beetles in my garden continue to multiply and eat all the fruit including grapes and cause the plants to die.
    Is there anyone who can give me the solution?

  13. Michele16 April 2018 at 10:41

    Basically an entire article not to mention a cabbage ... Either you take them off by hand or you stick them. Well ...

    • Matteo Cereda16 April 2018 at 15:02

      Hi Michele, criticisms are welcome. As you may have noticed this article is the answer to a user's question: I have been asked what to do and I have written what I know, if anyone has other methods to fight the beetles they are welcome. I explained the importance of prevention (which is carried out by turning the soil) and the possibility of using natural antagonists (in this case nematodes). Of course, in the small-scale organic garden when infestation has started, there are no useful natural solutions to my knowledge, so the option of manual harvesting remains valid.

  14. Maria Rosaria Lupo30 July 2018 at 15:05

    Is it possible that these vermons are also found in green plant pots? Today, moving a jar that had made a hole in the earth, I discovered a myriad of these white worms with a dark mesdo, from the description and the image they are the same. Anyway I changed the vase, cleaned everything up and hopefully they will recover. I forgot the roots of a succulent plant all eaten and now I understand why they suffer

    • Matteo Cereda30 July 2018 at 16:36

      I confirm, they can also be found in vases. Beetles make no big difference between field earth and pot earth.

  15. Giuseppe Bruno2 November 2018 at 17:23

    I found as many insects on the root of turnips as I can get rid of them

    • Matteo Cereda2 November 2018 at 22:04

      You need to understand what kind of insects they are, if they are actually beetle larvae you can try using neem oil.

  16. Shio11 November 2018 at 13:23

    Attention, generally those in the compost are not beetle larvae, but of Cetonia, very useful in the degradation of the organic matter of the compost.

    • Matteo Cereda11 November 2018 at 15:25

      Very true, thanks for the useful note, I add it to the post. The difference between cetonia and beetle is in the forelimbs, which for the beetle are well developed, in the cetonia instead not.

  17. Daniela20 June 2019 at 22:05

    but don't nematodes also eat roots? so I found on interenet

    • Matteo Cereda21 June 2019 at 6:26

      There are several species of nematodes, there are root-knot nematodes that cause damage to the roots, but also entomopathogenic ones that are very useful in the defense of the vegetable garden.

  18. Luca26 September 2019 at 21:09

    What to do against a significant infestation of beetle larvae? There are all sizes, from large to small. There is talk of dozens of individuals per square meter. Unfortunately, manual harvesting and hens are not enough. I believe adults have found the perfect place to lay eggs.

    • Matteo Cereda27 September 2019 at 8:33

      When manual harvesting is not enough and even the hens that I know of, the only way is entomopathogenic nematodes. But have you tried to work the land with the hens scratching behind? They are devastating sweepers.

  19. petrulli vittorio18 August 2020 at 19:31

    I have eaten the potatoes. In a few square meters yesterday I found at least 8 of these larvae I would like to get rid of these beasts

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