In our constant quest at the Garden Centre for pest control without harmful chemicals we have, at last, managed to get hold of diatomaceous earth, or DE as it is commonly known. What on earth is that, you might ask! Diatomaceous Earth is a creamy-white talc-like powder, a soft, crumbly, porous sedimentary deposit that is actually the fossilised remains of marine phytoplankton, algae-like plants called diatom. Their skeletons are made of a natural substance called silica. Over a long period of time the diatoms accumulate in the sediment of rivers, lakes and seas. Nowadays, we mine those silica deposits. Silica is very common in nature and makes up 26% of the earth’s crust by weight; it is the second most abundant element found in soil. Some types of silica we would recognise are rocks, sand, clay, glass, asbestos, quartz and emeralds. It is also abundant in plants and plays a role in their growth and development. Its composition is approx. 78% silicon, 10% calcium, 5% sodium, 3% magnesium, 2% iron and several other
trace elements. Significantly, whilst an effective and safe insecticide, it also feeds and nourishes our plants at the same time.
Diatomaceous Earth is not poisonous and it does not have to be consumed by insects to be effective. Interestingly, because of its porous and abrasive nature, it works as an insectide on any bugs with an exoskeleton – things like ants, fleas, ticks, cockroaches, bed bugs, spiders, earwigs, aphids, thrips, scale insect, beetles, scorpions, slugs and snails. It causes the insects to dry out and die by absorbing all the fats and oils from the cuticle of the exoskeleton and then, literally, sucking the insect dry. It may
sound rather macabre but, dehydration is quick and death is, apparently, rather rapid! It is not harmful to mammals, including humans, because we have an internal skeleton with a layer of skin to protect us.
We can eat it; in fact, we do eat it – probably without knowing – because there are thousands of non-pesticide products that contain food-grade diatomaceous earth. Things like toothpastes, skin-care products, medicines, water filters, paints and food and beverages. Many grains, for instance, are
stored with diatomaceous earth because it stops bugs from eating the grain and it is used as a clarifier for both wines and beer Diatomaceous Earth has several benefits. Insects cannot build up a resistance to it, as is the case with many chemicals. It does not lose its effectiveness; as long as rain does not wash it away, it is working. And, as long as it is kept dry, its shelf life is infinite. It is 100% natural and is,
thus, harmless to ourselves, children and pets. In fact, it is often used to control fleas and ticks in animals. Just sprinkle it in their bedding, leave overnight, then wash to remove. It can also be applied direct to the pet´s skin, leave for a day or two to have effect, then shampoo it away. It is also
used to treat mites in chickens. There are people that take food-grade DE internally; silica is required by bones, cartilage, tendons, blood vessels and most of our vital organs.
Please note that there are different grades of DE; that used for swimming pool filters can be dangerous. Exercise common sense as always. DE powder is extremely fine; try to avoid breathing it in. Large scale inhalation can cause irritation in nasal passages and lungs, with coughing and shortness of breath, especially in asthmatics. Once the powder has settled, it will not cause any problem.
It is especially useful where you have an insect problem. It can be sprinkled, very finely, onto ants’ nests, cockroach runs and in doorways where insects may be entering. Sprinkle it around your plants to prevent slug/snail damage; around pots to kill/prevent vine weevil and even directly onto plants with aphid/scale insect infestations. It´s a good one, for instance, to kill off the cochineal beetle that is sucking dry our prickly pears. It will be effective until heavy rain washes it away. If you prefer, it
can also be diluted in water and sprayed onto plants.
Now to the nitty-gritty – what about our beneficial insects, our bees, lacewings, ladybirds, earthworms? Well, research shows that earthworms are not affected by DE; the worms’ gooey mucous coating that helps them glide through the soil protects it. Equally, the furry coating of bees helps to protect them from the cutting action of the powder. However, it is not a desirable thing to have around bees or in their hives, so use it cautiously.
Bees are said to avoid it but do not dust DE onto flowers and never use it when bees are around – so apply it late evening. Use sensibly, and only where needed. If you have some sort of infestation in a fruit tree, for instance, spray/dust the tree late evening and wrap it in an old sheet, sealing it tight. Leave for a couple of days, then hose down the tree; the DE will wash away, providing a liquid fertiliser for your tree at the same time and keeping the bees safe.
And a final tip for smelly shoes! Dust DE in them and, magically, overnight all those horrible odours disappear!
We have 500g pots for sale in the Garden Centre for €7, so come and be earthy – and less smelly!
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