Does Diatomaceous Earth Kill Spider Mites?

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There are a few unavoidable certainties in the wide world of plant care. One of the most frustrating is that one or more of your plants will have a pest problem at some point.

Of these, one of the more annoying pests is spider mites. These tiny arachnids build web bridges between leaves and branches and are small enough to hitch a ride on the breeze to reach nearby plants.

spider mites feeding on plant leavesPin

Plenty of pesticides exist to deal with these frustrating critters, but who wants chemicals?

Neem oil is highly effective but may work too slowly against an advanced infestation.

Thankfully, there’s another all-natural solution you might not have considered to kill spider mites: diatomaceous earth.

Can You Use Diatomaceous Earth For Controlling Spider Mites

Diatomaceous earth is made from the fossilized remains of tiny aquatic organisms called diatoms. Their skeletons are made of a natural substance called silica.

Believe it or not, diatomaceous earth (DE for short) isn’t just a ground treatment and can be used against spider mites.

However, using the organic pesticide on foliage has a lot of drawbacks.

Here’s all you need to know about using DE to combat spider mites (and other leaf-born pests).

How Diatomaceous Earth Works

DE is generally sold as a powder but is far from smooth when viewed under a microscope.

Diatomaceous Earth works when the mites crawl through the Diatomaceous Earth dust to feed on the hens at night.

The powder is made of the crushed fossilized remains of diatoms.

This powder is perfectly safe for both humans and pets.

However, it’s always best to wear a dust mask when applying DE because you’re dealing with dust. Also, only use Food Grade Diatomaceous Earth.

So feeding diatomaceous earth to chickens in the right amount may be beneficial to their egg production. 

For smaller critters such as insects, Diatomaceous Earth is deadly. Diatomaceous earth, however, can be used as a natural chicken louse and mite treatment.

DE works effectively to exterminate the lice and mites but remains a safe pesticide to have come in close contact with chickens; it targets both full-grown and gestating mites and lice.  

The shell fragments lacerate both their exoskeletons and any protective coatings.

As a result, the pests dehydrate and soon die.

Diatomaceous Earth and Foliage

Diatomaceous Earth is a wonderful ground treatment, but there are some problems with applying it to leaves.

The most obvious issue is that DE is a powder and loses effectiveness when wet.

Since spider mites prefer to hide out on plant leaves’ undersides, it’s challenging to get the diatomaceous earth on infected plants.

This is compounded by the fact that it must be reapplied after rain and maybe dislodged by the wind.

The good news is that these factors can be avoided with container ornamental plants, making DE a finicky but viable option.

Applying Diatomaceous Earth To Leaves Of Potted Plants

As mentioned previously, DE isn’t an easy solution for foliage infestations, but it can be used with a little bit of patience. 

Begin by putting on gloves and placing the infested plant into isolation in a spot where it’s sheltered from breezes.

Yet there are many other organic pest control methods that we rely on too, and more readily than we reach for the DE – including preventative measures, companion planting, manual removal, and more. 

Diatomaceous Earth is effective against any insect that has an exoskeleton. 

This includes the following: 

  • Fleas
  • Mites
  • Lice
  • Ants
  • Aphids
  • Ticks
  • Millipedes
  • Earwigs
  • Cockroaches
  • Silverfish
  • Bed bugs
  • Crickets
  • Centipedes
  • Pill bugs
  • Sow bugs
  • Most beetles
  • Fungus gnat larvae and some grubs

It can be used on animals and birds to treat external parasites (lice, fleas, mites) and even internal parasites (worms). It’s one of the most popular items that we at the BHWT advise to use to combat red mites.  

You can then pour some Diatomaceous Earth into your hand and gently rub it onto the leaves’ tops and bottoms.

Avoid using pressure, as the DE can damage the leaf surfaces of indoor plants if pushed in.

It should never be used indiscriminately on flowers or plants, as it can harm beneficial insects.

A shaker is also a great way to dust the plants, although this won’t tackle leaves’ undersides.

The good news is that the DE can get caught in spider mite webbing, lacerating them as they travel along these artificial bridges.

You can also use a paintbrush to safely apply DE to both the tops and bottoms of leaves.

This method reduces the risks caused by applying DE by hand.

NOTE: As a natural insecticide Diatomaceous Earth also helps control slugs and snails in the garden.

Reapplying and Effective Time

Diatomaceous Earth must be reapplied every few days if it’s easily dislodged, and a new coat must be applied if the leaves get wet.

As a result, DE can take several days to a week (or even longer) to eliminate foliage-based pests.

When using DE in this manner, it’s meant to pair it with ground dusting, and a neem soil soak for maximum killing power.

Related: Learn How and Why you should use Diatomaceous Earth for Fungus Gnats.

The Bottom Line: Should You Use DE for Spider Mites

The amount of effort involved in using Diatomaceous Earth on foliage generally makes it a poor choice, even though the powder itself is highly effective.

We can see three instances where it might be a good option, however:

  1. You discover spider mites and have Diatomaceous Earth on hand to use while waiting for neem oil or another shipped product.
  2. You are treating smaller or young container plants that can be isolated in the right environmental conditions.
  3. You’re using DE on the soil and doing the shake method (shaking the plant to knock off loose bugs into the DE), then sprinkling DE onto the webbing and tops of leaves.

Keep in mind that DE only takes a few days under normal conditions but can take longer when used on foliage, so only try these methods if you don’t have a more efficient one at hand.

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