Updated: Jun 13, 2020
Diatomaceous Earth, aka diatomite, is a naturally occurring substance mined from certain lake-bed deposits. Diatomite is a great, non-toxic, way to control pests in your garden. It is effective against all insect pests that crawl on plants: ants, centipedes, aphids, cutworms, crickets, Japanese beetles, millipedes, slugs, snails, sow bugs and squash-bugs.
Diatomite is made up of fossilized diatoms, single-celled aglae which has a cell wall made of silica. The silica rich shells of these organisms give diatomaceous earth its exceptional porosity and abrasiveness. It has many uses, from agriculture to polishing agents.
Choose the right type
There are three different types of diatomaceous earth, food grade, pest control grade, and pool grade. Do not get the pool grade, it is used for swimming pool filtration and it is not suited for consumption or gardening.
Make sure you purchase plain crushed diatomite that is food grade, and does not contain any pesticides or chemical additives. The diatomaceous earth that contains mainly amorphous silica is generally used for agricultural purposes.
How it works
When insects crawl of diatomite, they get tiny cuts, which cause the insects to leak body fluid and die from dehydration. This substance also absorbs the fats from the bug's exoskeleton which also causes dehydration.
How to use
Diatomite is most effective when the soil or area is dry. Wet soil or rain will cause the diatomaceous earth to sink into the soil, rather than sit on top.
Use diatomaceous earth in wall crevices, steps or walkways, even the entrance to your garden beds. Target the base of plants where beetles, slugs, snails may crawl. The powder can be sprinkled onto the leaves and stems of plants being infested with insects. Apply a puff directly to insects, coat them completely, to kill them directly.
Just a side of caution, diatomite is non specific, it can also kill beneficial insects such as honeybees and ladybugs. To avoid that situation one option would be to cover your treated plants. After a day or two, uncover the plants and wash off the diatomaceous earth residue with a hose.
Another option would be to apply the diatomaceous earth to areas bees won't come in contact with. Don't apply this substance on blossoms or on foliage immediately surrounding them. And don't fret, bees are not as vulnerable as they seem. They have ways of protecting themselves against diatomite, and some simply learn to avoid the area being treated.
In addition to being a useful tool in gardening, food-grade diatomaceous earth is also used as a dietary supplement.
Happy Gardening! Feed the bees!