Diatomaceous Earth are the remains of diatoms prehistoric microscopic phytoplankton (single celled plants) that lived in the ocean millions of years ago. Large deposits of Diatomaceous Earth (DE) can be found throughout the world and is mined for a variety of uses. The majority of DE is used to control insect pests, such as weevils, in stored grains, used for human consumption. The rest is processed and used in filters such as for swimming pools and processing beer. It is also used in toothpaste.
OK, so the stuff is relatively safe since the EPA has approved it for various insecticidal and food supplement uses, not to mention in toothpaste. However, it may not be the safest to breathe and it is recommended when using it a dust mask is worn; however the only incidents of cancer can be found in humans that are mining the stuff for over 20 years.
DE does kill insects. It has been proven to be effective in killing insects, by the USDA and other researchers. Supposedly since it is made up of very sharp silica it makes cuts in the exoskeletons (insects skeletons are on the outside of their body if you remember your biology) causing dehydration and dries the little buggers up. Now this is where my logical mind says – how in the world can it cut up an exoskeleton and still be safe for human consumption. It does irritate the eyes and you shouldn’t inhale large quantities, but my brain says well heck if it can cut up a hard skeleton I shouldn’t breath any of it in! But regardless, it kills insects and it is safe for humans – WIN- WIN!
So how about for fleas? Fleas are insects. Look all over the internet you can find that it is recommended by many places that it will keep fleas under control (usually by the people and companies selling DE). So does it work?
I did some research and DE has to be dry to be effective. It works well – 100% kill of fleas in dry conditions. If DE gets wet, it is not effective – the research shows it is less than 20% effective when wet. So what does this mean? It will not work outside in areas such as where I live, near Chicago, because of the dew in the mornings and the rain. Now there is another problem with using it outdoors, the concentration needs to be higher than just a dusting. Research from the Texas Department of Agriculture (Laboratory Evaluation of Diatomaceous Earth for Control of Cat Flea) showed that it was necessary to have a 2.5% concentration of DE to soil for it to have a 99.6% effective kill. So that means 2.5% of the soil needs to be diatomaceous earth for it to work effectively, a light dusting will not provide that type of concentration.
Practically – it is impossible to treat your yard in the Midwest for fleas using DE. In Arizona, it would work, if you use a large amount to make sure you have a high enough concentration in the soil.
So it seems that it will work on fleas and if used appropriately such as indoors and in your pet’s bedding, it can be an effective control. Possibly even on your dog, if you could get enough to stay on the skin and your dog doesn’t become wet.
Now on to horses – some say it is an effective control against internal parasites for horses. Hmmm – DE not very effective when wet so I am not sure how that is going to work when the insides of a horse are pretty wet. Off to do some more research.