Understanding Diatomaceous Earth: A Natural Pest Control Solution

Diatomaceous earth (DE) has gained popularity as a natural and effective solution for pest control in gardens and homes. DE is derived from the fossilised remains of diatoms, microscopic aquatic organisms. It’s a chalk-like powder that can deter and eliminate a wide range of pests without the use of harmful chemicals. Below, we’ll discuss the intricacies of diatomaceous earth, explore its applications, discuss its effectiveness against different pests, address safety concerns, and provide tips on how to use it for optimal results.

What is Diatomaceous Earth?

Diatomaceous earth is a sedimentary rock that is composed of the fossilised remains of diatoms, which are ancient, single-celled algae. These diatoms have hard, silica-based shells, making them ideal for creating a natural insecticide. DE comes in various grades, but for gardening and pest control purposes, it is best to use food-grade DE, which is safe for humans, pets, and the environment.

How Does Diatomaceous Earth Work as a Pest Control Agent?

The unique structure of DE makes it an effective pest control agent and when pests come into contact with DE, the microscopic, sharp edges of the silica particles penetrate their exoskeletons, causing dehydration and eventual death. The abrasive nature of DE also damages the respiratory systems of insects, further contributing to their demise. This mechanism of action makes diatomaceous earth an excellent solution for controlling pests with exoskeletons. Those are mainly ants, beetles, fleas, cockroaches, and bed bugs. However, it is also effective at stopping slugs in their path.

The Effectiveness of Diatomaceous Earth Against Different Pests

Diatomaceous earth is a versatile pest control solution that can effectively target a wide range of insects. Here’s a breakdown of its effectiveness against common pests:

Aphids and Caterpillars

While diatomaceous earth may not directly kill aphids and caterpillars, it can act as a deterrent due to its abrasive nature. By creating a barrier of DE around plants, you can discourage these pests from infesting your garden.

Slugs and Snails

Slugs and snails dislike crawling over diatomaceous earth due to its sharp particles. Sprinkling DE around vulnerable plants or creating a ring of DE can help protect your garden from these slimy pests.

Fleas and Bed Bugs

Diatomaceous earth is highly effective against fleas and bed bugs. Its abrasive properties penetrate their exoskeletons, leading to dehydration and death. Apply DE around pet bedding or infested areas to eliminate these pesky parasites.

Ants and Roaches

Ants and roaches are no match for diatomaceous earth. By creating a barrier of DE around entry points and infested areas, you can deter these insects and prevent them from reaching your home or garden.

Other Insects

DE can also target mites, millipedes, earwigs, silverfish, crickets, and other insects with exoskeletons. Its ability to dehydrate and damage their protective layers makes it an effective natural pesticide.

Sap sucking Scale insect on a plum fruit tree branch closeup.

It is important to note that it is not effective against all pests. For instance, it may not be as effective against caterpillars with thick mucus layers or earthworms, which have adaptations that protect them from its abrasive effects.

Using Diatomaceous Earth Safely and Effectively

While diatomaceous earth is generally safe, it is crucial to take precautions to ensure its proper and safe use. Here are some guidelines for using DE effectively and without causing harm:

Choosing the Right Type of Diatomaceous Earth

When purchasing diatomaceous earth, opt for food-grade DE, as it is the safest option for use in gardens, homes, and around pets. Avoid using DE intended for pool filtration, as it may contain higher concentrations of silica and other impurities that can be harmful to humans and animals.

Applying Diatomaceous Earth

To use DE as a part of your pest control arsenal, follow these steps:

  1. Identify any Problem Areas: Find out where the insects are likely to infest or present themselves. Look for signs around entry points, crevices, or areas around plants.
  2. Create a Barrier: Sprinkle a thin, even layer of diatomaceous earth around the affected areas. Ensure that there are no gaps in the barrier that pests can easily pass through.
  3. Dusting Leaves (Optional): If pests are damaging the leaves of your plants, you can lightly dust them with diatomaceous earth. However, avoid applying DE directly to flowers to protect pollinators. Use an applicator for more accuracy and to keep your other tools free from the substance.
  4. Reapplication: Diatomaceous earth loses its effectiveness when wet, so it is important to reapply after rainfall or heavy dew. Regular reapplication ensures continuous pest control.

Safety Precautions

While diatomaceous earth is generally safe, it is important to take precautions to avoid inhaling the fine particles. When applying DE, wear a dust mask and eye protection to prevent irritation. Avoid creating airborne clouds of DE and keep it away from high-traffic areas to minimize the risk of inhalation.

Diatomaceous Earth Products

Additional Uses and Benefits of Diatomaceous Earth

DE offers several additional benefits beyond pest control. Here are some ways you can make the most of this natural substance:

Soil Improvement

DE can improve soil structure and drainage. Its porous nature allows it to absorb excess moisture, reducing waterlogging and promoting healthy root growth. Incorporate DE into your garden soil by mixing it in the top few inches or adding it to your compost pile.

Silica Source for Plants

DE is a valuable source of silica, an essential nutrient for plants. Silica contributes to stronger cell walls, improved drought resistance, and increased overall plant health and through using diatomaceous earth in your garden, your plants are going to benefit from the extra source of this mineral.

Livestock and Poultry Health

Diatomaceous earth is commonly added to livestock feed as a natural dewormer. It can help control internal parasites in animals, promoting their overall health and well-being. Additionally, DE can be used in poultry environments to combat mites and lice.

Environmentally Friendly

It is a natural pest control and it poses minimal risk to the local environment. It doesn’t cause harm to the soil, nor to any local water sources, birds, or other wildlife, and when used responsibly, DE can be a sustainable and eco-friendly pest control solution. One of the only drawbacks is that it is not as targeted as some biological pest controls.


Diatomaceous earth is a versatile and effective natural pest control solution. Derived from fossilised diatoms, it works by dehydrating and damaging the exoskeletons of insects, leading to their demise. DE can target a wide range of pests, but it is important to use it selectively and with caution to avoid harming beneficial insects and pollinators. By following proper application techniques and safety precautions, you can harness the power of diatomaceous earth to protect your garden and home from unwanted pests while promoting a safe and environmentally friendly environment.

Slug Pest Solution: Nemaslug (Nematodes for slugs)

Nemaslug Description

Phasmarhabditis is a tiny parasitic eel worm (nematode), barely visible to the naked eye, which occur naturally in British soils.

Nemaslug contains these nematodes for slugs mixed with a carrier medium.

Nemaslug Life Cycle

The nematodes live in moisture surrounding soil particles, they seek out slugs and enter them under the mantle.

Once inside the slug, the nematodes release a bacteria. Infested slugs will stop feeding within five days and go underground to die.

The nematodes reproduce inside the slug as it dies and are released back into the soil after the slugs death to infect more slugs.

Slug damage on a large Hosta plant

Typical damage caused by slugs.

Nemaslug Use

  • It will control most ages and species of slugs. Small to medium sized slugs burrow underground during the day, where it is moist. Large slugs over 8 cm, which are found in some parts of the country, are less able to burrow underground and therefore tend to live on the soil surface, it is less effective at controlling these.
  • It may affect water snails. To avoid harming water snails keep the treatment 3m away from ponds.
  • It should be applied to moist soil or compost, the area treated should be kept moist by normal watering after application to enable the nematodes to swim in the soil moisture.
  • It needs a minimum soil temperature of 5ºC (40ºF).
    NB. Soil temperature is more stable than air temperature.
  • It is simply applied as a drench, and will be effective for at least 6 weeks after which time a repeat application may be necessary.
  • It can be kept in a fridge NOT freezer at 5ºC for use before the pack expiry date (about one to two weeks after delivery date), however it is best used immediately upon receipt.
  • It is harmless to children, pets and wildlife. 

Nemaslug is recommended outdoors between 1st March and 31st October. Under protection they can be used any time if temperatures exceed 5ºC.

Slug Control Products

Pest Problems Explained – SLUGS

Slug Description

The adult slug is familiar to most gardeners! They come in a range of sizes and colours depending on the species.

The field slug is small (2cm) and grey, while the round back slugs can be relatively large (5-10cm) and black or brown in colour. in some cases round black slugs can have vibrant orange colouring on their foot.

Slug Damage

 Slugs are capable of feeding on flowers, leaves, stems, roots and seeds.

Leaf damage is usually shown as leaf shredding or severe notching.

Young plants are most at risk as the leaf feeding can be so severe that the plants die.

A Hosta with extensive slug damage

What is seen less often is the damage they cause below the soil surface to seeds, roots etc. This damage can result in seed that does not germinate, and in the case of potatoes, a very poor and damaged crop (see picture above).

Slug Life Cycle

Slugs are hermaphrodite, so every individual can lay eggs – up to 300 each slug. Eggs are laid in batches, usually 10-50, in moist but not waterlogged soil.

Most species found in gardens have an annual life cycle lasting less than a year, and lay eggs in any month providing conditions are suitable.

For example, field slugs hatching from eggs laid in the spring will become adults and lay eggs in the autumn. Eggs laid in the autumn will develop into adults the following summer. Because its generations overlap, all stages of the field slug are present throughout the year.

Many slugs spend most of their life below the soil surface tunnelling, rather like earthworms. Those seen on the soil surface represent only a small part of the total slug population.

They have a remarkable ability to survive during dry and cold periods by remaining deep in the soil.

Biological Control of Slugs

Slugs can be controlled biologically by using their natural enemy, the nematode Phasmarhabditis also known as Nemaslug.