Are nematodes dangerous for humans and animals? Is the use of nematodes harmless?

Anyone who wants to use nematodes against pests of indoor or agricultural plants often asks the question whether nematodes, also known as threadworms, are dangerous for humans and pets. This article brings light into the darkness.


Natural beneficial organisms in the soil

Nematodes, are introduced into the soil of the plant with the watering water. In the soil the microscopically small nematodes then eat the larvae of root pests, such as the larvae of the annoying fungus gnat. SF nematodes (Steinernema feltiae) are usually used to control indoor plants. When the nematodes have destroyed all pest larvae, they can no longer find food and die. The nematodes are not dangerous for humans, animals and the plant itself.

Nematodes are also used in organic farming to destroy pests without resorting to aggressive poisons. The big advantage: other insects such as bees are not affected by the useful earthlings. There is no more biological and environmentally friendly pest control. For this reason, more and more beekeepers and environmental protection associations are advocating the use of nematodes instead of poisons.


No danger for humans and animals

Nematodes live in the ground. There they find their food, like the larvae of the fungus gnat, and favourable living conditions. In the plant soil it is dark, constantly warm and sufficiently humid. Outside the plant soil the nematodes die, which is why they do not pose any danger outside the soil. As soon as the nematodes can no longer find food in the soil, they die. For humans, animals and the plant itself the nematodes are therefore harmless. Nevertheless, potting soil treated with nematodes should not be eaten, but due to various ingredients it should not be eaten. It does not taste good either.

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Fight fungus gnats effectively

In private households, nematodes are most commonly used against the larvae of the fungus fly or fungus gnat. The larvae of this annoying mosquito reproduce in wet plant soil and after hatching, countless small black flies fly around the house, similar to fruit mosquitoes. Anyone suffering from such a symptom should first look out for the infested plant. The nematodes are supplied as a kind of powder. This powder is poured into a watering can and the infested plant is then watered with this water according to the enclosed instructions for use.

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Thus the larvae in the plant soil are destroyed, but the already hatched fungus gnats still fly around in the apartment. To catch the hatched specimens as well, the use of so-called yellow plugs is recommended. The yellow, sticky plugs are placed above ground near the infested plant. The fungus gnats then fly onto the sticky surface of the yellow plugs and die there.

After about 3 days there should be a considerable improvement and after about 1 week most fungus gnats and larvae should be history.


Prevent moist potting soil and fungus gnats

Most pests in the soil of indoor plants are due to excessively moist plant soil. The use of plant granulate can help here:

  • Plant granulate stores water, but does not release it in excessive quantities to the roots. Plants are not over-watered and pests do not settle.
  • Plant granulate does not provide a breeding ground for pests. They cannot move in the plant granulate and cannot find food there.


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Bei allen genannten Links handelt es sich um Amazon-Affiliate-Links. Durch einen Klick auf einen Affiliate-Link werde ich prozentual an Euren darauf folgenden Amazon-Einkäufen beteiligt. Dieser Umstand beeinflusst aber nicht die Hintergründe meiner Produktempfehlung. Diese Produktempfehlung erfolgt unabhängig, ehrlich und aufrichtig.