Diatomaceous earth

Diatomaceous earth is a naturally occurring sedimentary rock composed of fossilized remains of diatoms, with amorphous silica being its active component.

Its action is purely physical, involving sharp microscopic edges that lacerate the exoskeleton of insects upon contact, causing structural damage.

The powder functions as a powerful desiccant by absorbing the waxy lipid layer of the insect's cuticle, which prevents water retention and causes rapid dehydration.

Since the death of the insect is caused by physical desiccation rather than systemic toxicity, it is impossible for pests to develop resistance to the substance.

The efficiency of the material is highly dependent on the particle size and its ability to cover surfaces uniformly to ensure maximum contact with target organisms.

The primary use of this substance is for the protection of stored grain against a variety of pests including weevils, flour beetles, and various grain mites.

In garden settings, it is widely used as a barrier control against crawling insects, particularly slugs, snails, and ants that damage young seedlings.

It is effective against soil-dwelling pests that reside in the upper layers of the substrate and attack plant roots or stems at the soil line.

Diatomaceous earth is also used in greenhouse operations to manage pest populations without introducing chemical residues to the edible crop parts.

• Weevils
• Slugs and snails
• Ants
• Flour beetles
• Soil mites

When used in grain storage, typical application rates vary between 0.5 and 1.5 kilograms per ton of grain, ensuring thorough mixing for effective control.

For agricultural and horticultural use, the powder should be dusted directly around the base of plants or on foliage, creating a continuous dry barrier.

Timing is critical: applications should be made during periods of low humidity and dry weather, as moisture quickly renders the powder ineffective.

In greenhouse settings, it can be integrated into the soil mix or applied as a top dressing to target soil-based life stages of emerging pest populations.

Re-application is necessary after every irrigation event or rainfall, as the physical barrier is destroyed when the powder becomes saturated with water.

The main limitation is that diatomaceous earth loses all insecticidal activity when wet, making it unsuitable for use in high-humidity or rainy conditions.

Proper protective equipment, including respirators, must be worn during application to prevent inhalation of fine silica particles, which can irritate lungs.

It is not selective, meaning it can also kill beneficial ground beetles and pollinators if they come into direct contact with the applied powder.

It has no systemic effect, which means it cannot protect against internal plant feeders or sap-sucking insects that do not contact the dusted surface.

Storage must be strictly in dry environments to maintain the desiccant capacity of the powder, as it readily absorbs moisture from the ambient atmosphere.