Diatomaceous earth (or DE) is generally considered one of the safest and most effective pest control methods currently available.
Diatomaceous earth is especially attractive for home and organic garden enthusiasts. The reason? Its ability to kill a wide range of bugs and soft-bodied insects without being harmful to children or pets.
Food grade DE is generally considered safe for human consumption. It is used both as a pesticide and dietary supplement.
But, fighting ants and cockroaches on the ground is very different from trying to fend off caterpillars chewing up your garden’s leaves.
Can you use diatomaceous earth against these pests, and if so, how?
Can Diatomaceous Earth Control Caterpillars?
Food Grade Diatomaceous Earth is a safe and effective pest management control mechanism for a wide range of pests, including caterpillars.
Be warned that you may need to treat the area frequently, as this control method can be washed away by rain.
How Diatomaceous Earth Affects Caterpillars
Both butterflies and moths are at their most vulnerable in the larval stage.
Their bodies are soft and generally slow-moving. This makes them an easy meal for many natural predators, ranging from ants to birds.
It’s this same soft body that gives DE an edge, as the short legs of a caterpillar cause it to rub the ground.
When the caterpillar’s body comes in contact with the sharp edges of DE, many tiny lacerations cause the caterpillar’s bodily fluids to escape, killing it.
Using DE Against Caterpillars
Fighting caterpillars with diatomaceous earth is slightly different from other garden pests. Dusting the ground around an infested plant will have little effect on them.
Thankfully, you can shake the powder onto the leaves directly using a duster or sifter.
When dusting plants, make sure to dust the leaves thoroughly and coat any caterpillars you run across.
Reapply after it rains and as needed, as moisture will cause the DE to clump and become less effective.
An Important Note on Dusting Outdoor Plants
Diatomaceous Earth is a wonderful product that is safe around larger creatures. But DE is unable to tell the difference between an ant and a honeybee.
When dusting outdoor plants to combat caterpillars, aphids, or any other leaf-born pest, avoid dusting near any flowers on plants.
Pollinators and beneficial friendly insects who visit a dusted plant can contact the DE, which can deplete the local bee population over time.
Use caution when dusting any flowering plants to avoid affecting any visiting pollinators.