Diatomaceous Earth

It's turning out to be a bad year for insects because of the mild winter and wet spring we've had.  There are lots of mosquitoes and chiggers, and I hear folks talking about how bad the fleas and ticks are. I'm trying to get back in the habit of applying insect repellent every time I go outside to work in the garden, or to go for a walk.  

I'm also protecting my dog from insect pests like fleas by applying a monthly topical flea treatment. I'm not thrilled about exposing him to strong chemicals, so I limit his exposure to times when the risk of infestation is greatest.  I am also taking preventive measures around my house to make sure that fleas can't get started in here.  Fleas can become quite an itchy problem if they get into your home; they can live in your carpet or in cracks and crevices, and hatch out generation after generation of blood-sucking little nasties.

Some people reach for bug bombs and cans of spray insecticides when fleas move in, but I have found less toxic protection that is still quite effective: diatomaceous earth. 



Diatomaceous earth, also known as DE, is made up of the fossilized remains of diatoms, microscopic one-celled plants that lived in ancient lakes and oceans. It crumbles easily into a white powder. DE is used as a filtration aid, a mild abrasive in products including toothpaste, a mechanical insecticide, absorbent for liquid, and in many chemical applications.

DE works as an insecticide because of its abrasive properties, and because it absorbs liquids like a sponge.  The fine powder absorbs lipids from the waxy outer layer of insects’ exoskeletons, causing them to dehydrate.  It can be used to help control and even eliminate ant, bed bug, dust mite, cockroach, silverfish and flea infestations. Diatomaceous earth kills insects by physical action, not chemical, so insects can’t develop an immunity to it.

Don't just rush out and get the first package you see of anything labeled diatomaceous earth.  There are two kinds, and only one of them is safe and effective as an insecticide. One kind of DE has been heat- and chemically-treated, and is used in swimming pool filters. You don't want to use this around food, food preparation areas, or pets.

To be effective as an insecticide, get the food-grade DE. This type has not been heat-treated, and the particles are smaller.  This type of DE is used in the US to protect stored grain from insects.  Because it is a fine dust, it is best not to inhale it. I just wear a dust mask when applying it. I find this DE at the garden center. 

Okay, so your pet has brought fleas into your home, and you want to get rid of them without using toxic chemicals.  Here's how to do it.

1.  Vacuum all your carpets and upholstered furniture every two or three days.  Before you vacuum, sprinkle a little DE across the carpet. Use a broom to gently brush it down into the carpet fibers. Let it sit for a couple of hours, or overnight is better; then vacuum.  If the infestation is really bad, you might want to vacuum every day for a while. 

2.  Flea comb your pet every day.  Drop any fleas you comb out into soapy water to kill them.

3.  Wash your pet's bedding a couple of times a week. When the bedding is dry, dust it with a little DE, making sure you get it into any folds or creases.

4.  Keep a paper-thin layer of DE wherever a vacuum can’t reach. Fleas hide in cracks and crevices, so you want DE in those places.  I use a turkey baster to suck up DE from the bag, then gently puff it along baseboards, inside drawers and cupboards, or anywhere you have an insect problem.  Remove electrical outlet covers and puff a bit of DE into the walls. I sprinkle it across my wooden floors and sweep gently to get it into the cracks between the boards.

Using the method I just described gives you inexpensive flea control; inexpensive, organic, and it works.  

DE is not a bait that attracts insects; the insects must walk through it for it to affect them. So don't have the DE in piles, but dust it lightly in any place they may hide.

Diatomaceous earth must be dry to work.  If it gets wet, or even damp, it won't kill bugs. 

DE is a very fine powder.  You can shake it from a shaker, scoop it with a large spoon, or puff it from a powder applicator, but don't try to pour it like you would sugar or sand.  Because DE is a very fine powder, it can be messy to apply.  Don’t have your fan on, and apply it carefully to keep it under control.  I use a turkey baster to suck up small amounts from the bag, then puff it gently along the crevice of the baseboards.

DE will not kill bugs instantly. It take a little time to wear through their exoskeleton and dehydrate them.  Apply it thoroughly as described above, and you should start seeing results in two or three days.  But don't quit!  Keep this treatment going, because bugs lay eggs.  A flea can produce new generations in about 2-4 weeks, and you want to break the life-cycle completely. 

Fleas have the typical insect life cycle: egg, larva, pupa (in a cocoon), and adult.  Only about 10% of the total flea population are adults at any one time. As a larva, the immature fleas mostly eat adult flea poop, or other organic matter, so keeping a clean house helps. Dry conditions are harder on them too.   When they are in the pupa form, they can't be killed by any pesticide.  Even if you killed every adult flea in your home today, more will be hatching out.  Make sure the DE is left out long enough for the new generation of hatchlings to come in contact with it. The key is to keep dusting and vacuuming for weeks, to get all the life stages of the fleas.

Even if you don't have a flea problem in your home, you can use DE as a preventive measure.  Every year in the spring, I dust DE into the cracks around baseboards and cupboards, around the backs of closets, and into electrical outlets, to keep insects of all kinds under control. As long as it stays dry, it will continue to be effective.

Some people even use DE on their pets for flea control.  I haven't tried this myself, but have only read about it.  For external application for dogs and cats, lightly rub food grade DE into pets' coat to dehydrate fleas, mites, lice and ticks. Dust them lightly but thoroughly, as in order to kill the parasites, they must come in contact with the DE. It can take up to 72 hours to dehydrate external parasites. Be careful, DE is very drying to the pet’s skin. Protect your pet’s eyes, nose and mouth while applying. Don’t apply it to your pet more than 2 or possibly 3 times a week. Apply it lightly and slowly to keep dust from flying everywhere, and then use a comb or brush to gently work it into the fur. 

When treating a flea problem, you have to tackle all three areas of infestation: on the pet, in the home, and in your yard as well.  DE is great for dry areas, but for moist areas like your lawn, beneficial nematodes are better. These microscopic nematodes attack flea larvae. Keeping your grass mowed will also help discourage fleas in the yard.

I am glad that there are ways to control insect problems that are safe to use around people and pets.   I would be very interested to hear if others have used some of these or other organic methods, and how successful they have been.