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  • Writer's pictureAndy Hemmer

Diatomaceous Earth for Aphids

aphids on a green leaf

Diatomaceous Earth (DE) for Aphids in the Garden: A Comprehensive Guide

Gardening enthusiasts often face the challenge of dealing with pests, especially aphids. These tiny insects can wreak havoc on your plants, leading to stunted growth, yellowing leaves, and even plant death if left unchecked. While there are numerous methods to control aphids, one natural and effective solution is diatomaceous earth (DE). In this comprehensive guide, we will explore what DE is, how it works against aphids, and how to use it safely in your garden.

What is Diatomaceous Earth?

Diatomaceous earth is a naturally occurring, soft sedimentary rock made from fossilized remains of ancient diatoms, a type of hard-shelled algae. It is commonly found in the form of a fine white powder and is composed primarily of silica, but also contains other minerals like calcium, magnesium, and iron.

How Does Diatomaceous Earth Work Against Aphids?

Diatomaceous earth works as a natural insecticide by physically damaging the exoskeletons of insects. The microscopic particles have sharp edges that scratch and dehydrate the waxy outer layer of the aphids, leading to their eventual demise.

Aphid Life Cycle, Habits, and Identification

Aphids are small, soft-bodied insects that come in a variety of colors, including green, yellow, brown, black, and red. They have long antennae and two tubular structures called cornicles, which protrude from the rear of their bodies. Aphids reproduce rapidly, with females giving birth to live young without the need for mating.

A single aphid can produce up to 80 offspring in a week. Aphids feed on the sap of plants, using their piercing-sucking mouth parts to extract nutrients. This feeding behavior can cause plants to become weakened and susceptible to diseases. In addition to damaging plants directly, aphids also produce a sticky substance called honeydew, which can attract ants and promote the growth of black sooty mold.

How to Use Diatomaceous Earth for Aphids in the Garden?

  1. Selecting the Right Type of DE: There are three main types of DE - food grade, filter grade, and crawling insect control grade. Food grade DE is safe for humans and animals and is suitable for use for food storage, cleaning, and deodorizing. But is not approved as a safe insecticide. Industrial grade DE, on the other hand, is heat-treated and contains higher levels of crystalline silica, which can be harmful if inhaled and is meant primarily for industrial uses like filtration. Crawling Insect Control Diatomaceous Earth is just as safe and natural as food grade but contains a label that certifies it to be a safe and effective pesticide by the EPA.

  2. Application: DE should be applied when the foliage is dry or just damp from a morning dew, as it is most effective when it remains dry. Sprinkle a thin layer of DE on the leaves and stems of the affected plants, focusing on areas where aphids are most likely to congregate.

  3. Reapplication: DE may need to be reapplied after rain or heavy dew, as moisture can reduce its effectiveness. It is also advisable to reapply after watering your plants. The rule of thumb is if you can see it and it will be able to dry out, it will be effective. However, if it is washed away by a watering or a rainstorm, please reapply when things dry out.

  4. Safety Precautions: Wear gloves, a dust mask, and protective eye-wear when applying DE to avoid inhaling the fine particles. Keep children and pets away from the treated area until the dust has settled.

  5. Avoid Direct Application to Flowers: Avoid applying DE directly to flowers, as it can also harm beneficial insects like bees and butterflies. Instead, focus on the stems and leaves where aphids are most likely to be found.

  6. Regular Monitoring: Regularly monitor your plants for signs of aphids and reapply DE as needed. It may take some time for the aphid population to decline, so be patient and persistent.

  7. Consider Companion Planting: Planting certain herbs and flowers like marigolds, chives, and garlic around your garden can help repel aphids naturally and reduce the need for DE.


Diatomaceous earth is an effective, natural, and safe solution for controlling aphids in the garden. By following the guidelines outlined in this comprehensive guide, you can effectively use DE to protect your plants from aphid infestations while minimizing harm to beneficial insects and the environment. Happy gardening!

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