The use of diatomaceous earth as an insecticide started thousands of years ago. China used diatomaceous earth as an insecticide 4,000 years ago. Birds take “dust baths” using soil and clay dust to fight off mites and other parasites. In the US, diatomaceous earth has been used as an insecticide to control codling moth larvae, flea beetles, bed bugs, cockroaches, ants, and other insects. A 2014 study showed diatomaceous earth as an effective insecticide for the German cockroach which had become resistant to popular insecticide sprays.

 

How Does Diatomaceous Earth Work?

 

Microscopic view of the diatom exoskeletons

Inert dusts, like diatomaceous
earth, kill insects by desiccation. The dust removes the outer layer of wax or
grease that is a part of an insect’s exoskeleton. It absorbs waxy fats and oils
from the epicuticle or skin of insects and other invertebrate pests. After the
insect’s coating is removed, it cannot retain water and dies from dehydration.

 

Diatomaceous Earth for Bed Bug Control

DE is a common insecticide replacement for treating bed bug infestations. When treating a pest infestation horizontal transfer of insecticides is important for effectiveness. Horizontal transfer describes the process of one insect transferring the active ingredient of a pesticide among other insects with the population through contact. A 2013 study demonstrated horizontal transfer of diatomaceous earth in the common bed bug. This is important because bed bugs live in hard-to-reach places, and horizontal transfer is needed for effective control.

 

Insect Resistance to Insecticides

Over the past several decades, insects have developed resistance to many chemical insecticides. An article presented at the Rutgers Entomology Centennial Symposium on Insecticide Resistance: Mechanisms and Management spoke to the challenge of insects ability to adapt to and develop resistance to chemical insecticides.

 

“The spread of genes for cross and multiple resistance among insect pests has rendered most of our present insecticides obsolescent, and very few novel insecticides are under development as substitutes,”

Robert L. Metcalf

Genetics and intensive insecticide
application are two significant factors that contribute to insecticide
resistance. Insects with genes that resist a particular insecticide or class of
insecticides survive and are thereby “selected” to pass on their
resistant genes to later generations.

 

Insect Resistance to Diatomaceous Earth

Diatomaceous earth is not a chemical insecticide. Diatomaceous earth is a dust-like substance that is found in nature. It kills insects by wearing away their protective was or oil on their skin, which leads to dehydration. Because DE acts as a desiccant, it is much less likely for insects to develop genetic resistance in the same way as chemical pesticides.

 

The US Department of Agriculture on DE

 

United States Department of Agriculture Logo

 

Tests conducted by the United States Department of Agriculture have demonstrated DE to be more effective than malathion in controlling a variety of insects, including the grain borer, rice weevil, and confused beetle. Tests showed that with proper climatic conditions and application, diatomaceous earth could be effectively used on field crops as well. A benefit would be the reduction of the amount of chemical residues in water, soil, and atmosphere.

 

Diatomaceous Earth as an Insecticide Replacement

Diatomaceous earth can be used as
an insecticide on a wide variety of insects including:

 

  • Aphids
  • Thrips
  • Ants
  • Mites
  • Earwigs
  • Bedbugs
  • Flea Beetles
  • Cockroaches
  • Snails
  • Slugs

 

How to Apply Diatomaceous Earth

Places that sell diatomaceous
earth as a replacement for insecticides will also sell different applicators.
Some applicators are small, and others are large and run on a motor. In your
garden, DE can be applied with a dust applicator designed for that use. It’s
essential to always wear a dust mask when diatomaceous earth. When applying
make sure to cover the top and underside of all the foliage with the dust. A
good time to apply is following a light rain or early in the morning when the
dew is present.

If you’re applying DE in the house
for bedbug control or other insect control, DE should be applied along
baseboards and the base of furniture.

 

Conclusion

Diatomaceous earth has been shown
by scientific studies to be an effective replacement for insecticides. It’s
been used for thousands of years, and it’s not surprising considering insects’
inability to become resistant. DE is a occurs in nature and has never been
shown to cause harmful effects on humans, pets, or the environment. If you’re
looking for a safe and chemical-free replacement for pest control, diatomaceous
earth is a great choice.