What are Nematodes? Why are they so beneficial?

What are Nematodes? Why are they so beneficial?

What are Nematodes? And why are they the best option for your garden?

Nematodes, also known as roundworms, are a diverse group of organisms that live in a wide range of environments, from deep ocean trenches to lush garden soils. The vast majority of nematodes are harmless and/or beneficial to their ecosystems. Unknown to many, nematodes are actually crucial for maintaining soil health, supporting agriculture, and contributing to ecological balance.


Pest Control

Nematodes are effective biological control agents against a variety of insect pests. They parasitize and kill pests such as caterpillars, beetles, and grubs, which can cause significant damage to plants and crops. By choosing nematodes as a natural pest control method, you can reduce reliance on chemical pesticides, which helps protect the environment and human health. This biological pest control is not only sustainable but also cost-effective, and really easy to use.

We supply nematodes for the prevention of:

Box tree caterpillars are quite distinctive with black stripes and white dots on a green caterpillar. Nematodes are a natural pest control safe for pets and children.

Viburnum beetles will damage and defoliate a wide range of Viburnum plant species. Most of the damage, however, is caused by the Viburnum larvae. The larvae are creamy yellow with black markings, around 8mm long, and will quickly shred leaves of Viburnums.

Asparagus Beetle is a serious pest of Asparagus plants. The larval stages and the adult beetles both feed on the plants, damaging the stems and foliage. The larvae are greyish-black in colour.

Caterpillars can damage plants by feeding on their leaves and flowers and can defoliate a plant and reduce its vigour. They also carry several pests with them when they migrate from the larval stage to the adult stage.

The Fungus Fly can cause severe damage to many plants including house plants and plants being propagated. They feed on roots and can spread soil-borne diseases.

Cutworms are moth larvae that feed on the stems of young plants, often cutting them down. They can vary in colour from brown to grey to black as well as green and pink, and some species may have stripes or spots.

Affects plums, damsons and greengages. The moths mate and lay eggs on the plum tree’s leaves and young shoots. The caterpillars hatch, tunnel into the fruits and feed on the flesh.

A major pest of agricultural crops and can cause significant damage if not controlled, feeding on fruits such as apples, pears, and walnuts. The larvae are often called "apple worms" because they bore into the fruit and make it ripen prematurely and become inedible. The adults are grey and have mottled wings that blend with the tree bark.

Chafer grubs are the larvae of the cock chafer, garden chafer and Welsh chafer. They live underground in the soil and feed on plant roots, which can become a major problem, especially in lawns. All three species of chafer grubs look the same but differ in size: creamy coloured, around 15mm in length, and have distinct legs.

They are the larvae of crane flies, which damage lawns, small plants, and vegetable plots by eating roots, causing lawns to develop patches where the grass turns yellowish brown. Leatherjackets have long tubular bodies, up to 30mm long, and are greyish brown. They have no legs or obvious head.

Vine weevils are destructive garden beetles that feed on plants during both stages of their life cycles. The adults are black in colour with a yellow mark on their wings. They cause damage by feeding on and notching the foliage of plants. The larvae feed on the roots and can cause severe damage, potentially leading to the death of the plant.

They are small, black-bodied flies that resemble common houseflies, about 1/4 inch long, with yellowish legs, wings, and heads. They are most active during summer and lay their eggs in the soil near root vegetables like carrots, celery, and parsnips. The fly larvae tunnel into the main root of the vegetable causing it to rot. The larvae are creamy yellow, tapering maggots, up to 9mm long and mainly found in tunnels in roots.


Soil Health and Nutrient Cycling

One of nematodes most significant contributions is their role in maintaining soil health and cycling nutrients around the earth. Nematodes feed on various soil organisms, including bacteria, fungi, protozoa, and other nematodes. This feeding activity helps regulate microbial populations and stimulates microbial activity, which is essential for the decomposition of organic matter. As nematodes consume bacteria and fungi, they release nitrogen in a form that plants can readily absorb. This process, known as mineralization, enriches the soil with essential nutrients, promoting plant growth.

The presence and diversity of nematodes also serve as a valuable indicator of a healthy soil. Different nematode species have varying sensitivity to environmental changes, such as pollution, soil disturbance, and nutrient levels. By monitoring nematode communities, you can assess the biological health of your soil.


Soil Structure and Aeration

Nematodes play a pivotal role in enhancing soil structure and aeration. As they move through the soil, nematodes create small channels that improve soil aeration and water infiltration. This physical activity helps prevent soil compaction, which is crucial for root growth and overall plant health. Well-aerated soil also supports a diverse and active microbial community, further enhancing soil fertility.



Nematodes are often overlooked but are indispensable components of many ecosystems. Their roles in nutrient cycling, pest control, soil structure maintenance, and as indicators of soil health highlight their importance to the environment. Embracing and understanding the positive aspects of nematodes can lead to more sustainable agricultural practices and a deeper appreciation for the complexity and interconnectedness of life beneath our feet. Their small size belies their significant impact, making them true unsung heroes of the soil.

View our full nematode range for pest control

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