Donna PorterIt's a Wonderful World of Plants

A Micro-Plant from the Past for Present and Future Use


By Donna Porter

A million or so years ago, when the earth was younger and the seas covered the land and freshwater seas were abundant, billions of algae -like organisms developed.   All of the waters of the earth where inhabited by microscopic one-celled, algae-type plants called diatoms (Melosira spp.).  These diatoms absorbed the minerals (mainly silica) from the water, creating protective shells or exoskeletons for themselves. They lived in quantities beyond the mind’s ability to conceive and provided nutrition and sustenance for other forms of sea life. As they died, their exoskeletons sunk to the bottom of the sea beds where vast deposits- thousands of feet thick – were laid down. When the waters receded, these huge deposits were eventually covered with land and the shells fossilized and compressed into a soft, chalk-like rock called diatomite or diatomaceous earth (DE).  Geological upheavals over the eons have exposed these abundantly-rich sedimentary deposits.

There are both freshwater and saltwater species of DE.  The most common freshwater species are Melosira granulata, Melosira preicelanica or Melosira islandica.  Freshwater species are superior to saltwater types, and are characterized by a highly-porous, filter-like, cylindrical shape of much greater strength.  Fresh water lake deposits of DE occur in Nevada, Oregon, Washington and California. Lake deposits of DE also occur in interglacial lakes in the eastern U.S., Canada, Germany, France, Denmark, the Czech Republic, Africa and Australia. In 1836, the first deposit of diatomaceous earth was discovered in Northern Germany (where it is called “kieselgur”). Through the history of man’s existence, uses have been found for these diatomite deposits, and today there are many ways for man to benefit from using this material.

When diatomaceous earth is quarried, milled, finely ground, screened and centrifuged, it becomes a fine talc-like powder. Proper milling is essential to crack apart the diatom skeleton and to expose the hard, microscopic silica spines.   This powder can be safely handled with bare hands, although it can cause drying of the skin with prolonged contact.   Diatomaceous earth is a non-toxic, inert material.  It is composed of 85% amorphous silica, and numerous other minerals including aluminum, iron, calcium and magnesium in higher percentages to potassium, phosphorus, manganese, titanium and other trace minerals.

DE is utilized industrially, agriculturally and for health purposes.  It has been used extensively as a pesticide for control of internal parasites in livestock and for insect control in grain storage in the U.S for nearly 50 years and for over 400 years in China, Egypt, Greece and Africa.  Unfortunately, its myriad of benefits have been largely forgotten (or perhaps intentionally concealed and unrevealed), and substituted by new, so-called “improved” technologies of the chemical pesticide industry in the last sixty years.  It all sounds too familiar of a story.


DE’s method of destroying insects is entirely mechanical /physical and unlike the action of chemical insecticides. The microscopic and razor-like construction of a diatomite fragment disrupts the life process of insects.  These razor-sharp spines are harmless to humans and other warm-blooded animals due to their size, as well as physical differences. The destructive effects of DE is solely to insects, whose frames (exoskeletons) are on the outside. Vital fluids of insects are held in and protected by an oily or waxy seal over a hard porous cover. If an object is small and sharp enough, it will scratch the insect’s waxy seal, allowing the insect to dehydrate and die. Minute sharp particles are also taken in internally by certain insects and interfere with their breathing, digestion and reproduction.


Among the list of pests that DE has been used successfully to control are:  ants, termites, slugs, snails, fleas, fly maggots, aphids, bed bugs, mites, ticks, cockroaches, earwigs, scorpions, cutworms, ear worms, lawn grubs and grasshoppers.  Complete insect control may take several days, and re-application may be necessary after a heavy rain.  Unlike chemical insecticides that act fast and have a short residual effect, DE works slower while remaining active and nontoxic as long as it remains in the environment.  DE is not harmful to earthworms, but unfortunately is detrimental to honeybees and other beneficial insects.  It is suggested to not apply to flowers.


The addition of Silica (the main mineral component of DE) has been proven to have beneficial effects to soils and to plant growth.  Over the years, through intense agricultural use of the land, silica has been depleted. This not only effects plant growth but the amount of silica found in our foods.  Studies suggest that only about 1/3 of the silica that we need is present in our fruits and vegetables.  Silica is a necessary component for the health of our tendons, cartilage, blood vessels, and bones. It is also needed for the health and strength of our skin, teeth and nails and contributes to the health of almost all of our vital organs, including the heart, liver and lungs. 


One of the oldest uses of diatomaceous earth has been cosmetically, as a toothpaste and facial scrub, due to its mild abrasive capacities, although its list of benefits for humans is extensive.  It has become most popular for its use in the elimination of internal parasites in humans and in animals, removing intestinal invaders and other harmful substances from the digestive tract, and stimulating digestion and the absorption of nutrients by sweeping foreign bodies out of the system.  It has gained even more popularity recently as a natural detox substance for humans.


Since 80% of DE’s volume is made up of interconnected pores and voids, its use as a filtering, filler and absorption material is well known.  Because of these qualities, DE is also used in baking mixes, shoe polish, cosmetics, body powders, cat litter, water filters, metal polishes, soaps, potting soil conditioners, hand cleaners, and beers and wines are filtered through it. Diatomaceous earth is FDA approved for internal and external use and has a rating of Food Chemical Codex Grade.  


The majority of swimming pool filtration systems now use “Pool Filter Grade” diatomaceous earth that has been heat and chemically treated and is toxic to animals or humans who ingests it.  It is always of utmost importance to only obtain “Food Grade” diatomaceous earth to use in and around your household or for animal or human use.  A local supplier of “Food Grade” DE here in the Quepos area is Johnny McDaniel at 2779-1103.  The only dangers that have been reported from the use of DE are through excessive inhalation or exposure to the eyes.


This incredible, natural, fossilized plant substance called Diatomaceous Earth has too many properties and benefits to list or to write about in one short article.  There is a wealth of information available on the web. For more in-depth scientific information and data, use “Melosira” in your google search.


Experimenting with natural substances like Diatomaceous Earth for use in the garden will be of major interest at the future botanical garden, so that these test results can be passed on to our visitors for their own benefit and for the benefit and safekeeping of our garden and natural environment as well.


Donna is a Horticulturist and has been living and working in Manuel Antonio for 8 years.  She consults, designs, installs and maintains gardens for private homes and hotels and also develops botanical trails. Donna is the founder and first Director of the Botanical Garden of the Ozarks and is pursuing the development of a botanical garden in, and for, the Quepos area.   [email protected],  2777-5149

One thought on “A Micro-Plant from the Past for Present and Future Use

  • Hello,
    I live in San Isidro del General (Pérez Zeledón). I am looking for a supplier of “Food Grade” Diatomaceous Earth for various purposes. I would like to get a large amount. Can you help me and/or send me the emil address of Johnny McDaniel.
    Thank you very much.
    Julie Foster

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