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Natural Non Toxic Control of Fleas

Flea Life Cycle

My Page on Fleas on cats has a more complete article on the life cycle of fleas and photos of fleas, and larvae.

The short version of the flea life cycle is this: A flea has a blood meal and lays eggs on the cat. The eggs dry and fall off the cat onto spots where the cat hangs out. Soon the eggs hatch into larvae that eat organic matter including flea dirt (adult flea poo rich in blood) that has fallen off the cat previously. The larva pupates into a cocoon and stays dormant for a short while or longer if there is no cat around, and when it senses a cat, hatches into a very hungry flea that jumps onto your cat.

Understanding the life cycle means that we know we have to treat 4 separate stages of flea development. Adults on cats, eggs on bedding and wherever the cats goes, larvae, and pupa. Eggs and Pupae are quite a bit more resistant than larvae and adults. In fact a pupa can hang around for several months just waiting for a nice juicy cat to come around before it comes out of its safe cocoon.

This life cycle also means that we have to treat several different areas to control fleas effectively

Although I speak of cat fleas, the cat flea is the flea that is most commonly found on dogs. It can also infest raccoons, skunks, opossums and other animals. It will also cheerfully bite humans but human blood lacks whatever it takes to allow the flea to lay eggs. In order to make eggs from human blood a flea needs to feed for over 12 continuous hours!

Because of the complex life cycle and wide range of locations it is unlikely that we can eradicate fleas completely. Most control programs aim at keeping flea population under control. Some insecticides are very effective but also highly toxic. Less toxic alternatives are available, (less toxic, not non toxic) can be effective but may have some side effect.

Why use less effective non toxic flea control alternatives?

When an animal is treated with an insecticide, everyone in the home gets treated. Although many products now offered are considered very safe, no one would suggest that they are harmless. Constant exposure to you, your children, and your animals to some low dose toxins can add up to significant effect over 15+ years of a cat's life. Since the products are designed to stay on the animal for several weeks exposure remains over long periods.

To this low level of exposure, add any residual exposure from eating fruits and vegetables which have been sprayed. The same insecticide, imidacloprid, that is used in Advantage spot flea treatment is also commonly used in crops spraying all over the world. It has come under question by the FDA in 2009 after reports of nasty side effects started adding up. I have a cat that cannot tolerate it and gets very sick, SO it's not just hearsay. Keep in mind though that these chemicals have been tested and for the most part are safer than having a nasty flea infestation. It is safer to treat with good quality flea treatments than not to treat at all.

Interesting article (item 12) on the safety of IMIDACLOPRID.

Other pesticides have been used to spray areas of bedding and floors. Some of these are considerably more toxic.

Parasitipedia.net has a great deal of information on different products. If you are looking at the toxicity of various insecticides it's a very good resource.

Alternative Treatment for Flea Control

Notice I said control. It will not be possible to completely eliminate all the forms of fleas if you don't use pesticides.

Any successful flea control program will mean a battle on 3 fronts

What can you do safely to control fleas on your cat?

Keep her healthy

A healthy cat is less likely to be overwhelmed by fleas. So step one is keep your cat healthy. This means good food, good water, safe surroundings. Medical help when required. All the usual things.

Keep your cat inside if possible. Most small animals around will carry fleas and your cat will get re infected when it goes out, it's not always possible but it helps.

A healthy energetic cat grooming properly can get rid of 50% of its fleas. Not bad. Older and younger cats are not so successful. It is possible that they don't have the skills, or the energy to be as successful.

The immune system of a healthy cat has been shown to help combat fleas.The immunity mechanism has not been clearly identified yet.

Your vacuum is your best friend.

Because eggs, larva and pupa all live off the cat you must get rid of these if you want to succeed. Vacuum anything you can't wash regularly. Cracks in the floors, carpets, furniture, your bedding, these are all potential homes to immature fleas. Wash bedding and cat cushions regularly in hot water and dry in a hot dryer. If this is not possible dry in the hot sunshine.

It helps to keep your cat away from spots you can't easily reach to clean, otherwise fleas will accumulate there and re infect your kitty. When you vacuum don't forget the carpet covered cat tree.

After vacuuming, dispose of the bag or content of the vacuum so that it does not re infect the cat. Fleas are tough and can survive in the bag.

If you don't object to mothball smell, putting a couple in the bag helps too. Thanks to the helpful reader who suggested this. Mothballs are toxic though so not too many.

Doing only this regularly will significantly reduce the flea population.

I have heard of cats who enjoy getting vacuumed. Mine don't but it would work to get fleas off the cat if she lets you.

Wash bedding in Hot Water

Washing your cat's bedding in HOT water and drying in a hot dryer can kill fleas. Larva are particularly sensitive to laundry but all phases of the life cycle can sometimes be killed. If laundry is not possible, ironing will help, just don't melt synthetic fabrics though.

Freezing is not as useful. I've seen adult fleas thaw out and jump around after spending several weeks in the freezer.

Many sources recommend flea combs

I have had no success at all using a flea comb except on a very small short haired kitten. The infestation would have to be huge for a comb to have much effect. I simply cannot get the hair through the comb, too furry by miles. It takes out the undercoat nicely though and I use it in the spring to great effect.

If you have a short hair cat with a thin coat a flea comb can help. Here is one on Amazon, Safari Flea Comb for Cats, Green

If this works for you keep a bowl of alcohol or hot soapy water nearby to put the fleas you collect using the comb.

Flea combs can be useful though, if you are trying to figure out if your cat has fleas. It can also be useful on kittens, or when you are bathing your cat. The fleas will tend to go to the head and you can use the comb to catch them.

Flea Traps

Many flea traps have been devised and they will catch fleas. Typically a sticky sheet or a soapy dish of water is placed below a light. The flea is attracted to the light and heat, jumps up and lands in the water or sticky sheet and dies. This is a method which can work to reduce the number of adults around but will not work on larva or eggs. It's an excellent way of figuring out if you have a lot of fleas around and where they are though.

Here is a commercial version of flea traps: Victor M230 Ultimate Flea Trap (Pack of 2, Multy)

Bathing is effective...but!

If you can convince your cat, bathing can be effective. It is sometimes possible to drown fleas if in the bath long enough. The flea will tend to run up to the head which is out of the water. They can be picked off with a flea comb. A mild shampoo helps but beware of strong anti flea shampoos. They can be quite toxic. If you make a ring of suds around the cat's neck, it will help stop fleas from fleeing up the drier head.

There is some suggestion that vinegar is somethings fleas don't like so adding some to the bathwater might help. Rinse after and don't get it in the cats eyes. Don't use a strong solution.

Some natural products will kill fleas

Pyrethrins are made from chrysanthemum flowers

Pyrethrins are potent insecticide acting as neurotoxins. At sub toxic level they act as insect repellant. They are non persistant because they biodegrade on exposure to light and oxygen. This helps prevent build up in the environment where it is used. It has a long history of use having been available for over 100 years.

FDA approves pyrethrins around food considering it as one of the safest insecticide around. It is quite toxic to fish though and care should be taken not to expose your pet fish to pyrethrins. When ingested in low levels by mammals it gets hydrolized and degraded by acids in the stomach.

It has some toxicity and direct contact needs to be minimal. Some cats are more sensitive than others and will show reactions at low level of exposure. Instructions need to be strictly followed. Products intended for dogs should NEVER be used on cats. Pyrthroids are synthetic substances with similar properties to pyrethrins but show significantly more toxic properties to cats. Permethrin should never be used near a cat. Even exposure to a dog treated with it is dangerous. Here is an article on pyrethrin toxicity

Here is another article comparing pyrethrin which is quite safe for cats and permethrin which is NOT at all safe.

Although Pyrethrin is quite safe in recommended doses, it is often combined with piperonyl butoxide to increase stability and make it more effective, this increases risks of toxicity to cats and should be avoided. Read the label carefully and follow instructions.

Pyrethrins are often added to diatomaceous earth flea powders. Check ingredients carefully.

Essential oils are effective insect repellant but MANY are toxic to cats.

The reason is that cats do not produce a liver enzyme (glucuronyl tranferase) that allows many other animals and humans to break down the hydrocarbons and terpenoids present in most essential oils. So it takes much longer for them to be eliminated from the cat's system. This slow elimination rate allows the toxic elements to accummulate faster than they can be eliminated by the liver.

These substances can build up in the liver and become toxic. If the exposure is high then buildup can be dangerous and fast. This can cause toxicity and liver damage.

Because of this, many essential oils INCLUDING CITRUS oils can be toxic to cats.

Lemon, orange, tangerine, mandarin, grapefruit, lime, bergamot, pine, spruce and fir, citronella, lavender, pennyroyal, rue, teatree oils are high in oils that should be avoided by cats.

Linalool found in lavender and coriander is also toxic for the same reason, as is limonene and citronella.

Phenols are also suspect and have been shown to be toxic to cats. Oregano, tarragon, savory cinnamon, clove and thyme oils all contain phenols.

Citronella, Limonene, Linacool all have flea repellant properties and are sometimes offered in flea preparations. They are quite safe for dogs because they can process them in the liver. They are much more toxic for cats and in lower doses. Avoid them if you can.

Citronella is extracted from various species of Cymbopogon trees found in Asia. It contains variations of: Geraniol, limonene, methyl isoeugenol, citronellol and citronellal. Sometimes geranyl acetate is present depending on the source.

The EPA has determined that citronella has little or no toxicity for humans

Web MD article on citronella used on humans.

Linalool is extracted from citrus peel for flea control of premises. It should never be applied to a cat.

Note that just because a product is natural, it is not necessarily safe. There are plenty of plants toxic to cats and humans. So beware of any supplier that claims a product is safe because it is natural.

Some Essential Oils are somewhat SAFER for cats.

These include Cedarwood, Peppermint, Rosemary, Catnip.

Article on aromatherapy and use of essential oils on animals. It suggests that some aromatherapists advocate NEVER using any essential oils on cats.

Keep in mind that essential oils are a CONCENTRATED form of bug repellant. Often the plant itself holds enough essential oils to be effective without any danger of toxicity. Keep in mind also that there is not a great deal of formal scientific research that has been done about the toxicity of essential oils on cats. Much of what is claimed on the internet is merely copied from unproven sources. I try to use formal scientific studies when available, or try to quote reputable sources. There is not very much available on this subject.

Catnip has been shown to be highly effective as an insect repellant and has not been blamed for high toxicity. Efficacy and safety of catnip University of Nebraska

Here is my catnip page

The bottom line on using essential oils on cats? Cats are VERY sensitive to poisoning from essential oils. If you plan to use some choose a non citrus non phenol type. Do not apply directly to the cat. Use only in highly diluted form.


Borax has been used for a long time as a way of killing fleas in carpets or in inaccessible spots. It is relatively safe and is commonly used to keep cockroaches away. It can be found in some laundry powders as well.

Borax should not be used directly on an animal. It should be used on carpets and cracks along floorboards, then vacuumed up. Borax will act as an herbicide so it should not be used outside. It will damage carpets if left in.

Borax can be toxic and should not be breathed in. Use a mask when applying and avoid raising dust while vacuuming.

Diatomaceous Earth kills fleas on contact

In order to be effective, diatomaceous earth must come in contact with the flea or the larvae. The sharp edges of the tiny shells that make up diatomaceous earth, pierce the flea and dry it out. It is sometimes combined with pyrethrin for better effect.

Food Grade Diatomaceous earth is not toxic on its own and can be safely used BUT it should not be breathed in as it can be quite irritating. It is listed for Organic Use. It can be combined with borax to treat carpets, but should be vacuumed up. Avoid breathing the dust and wear a mask. Sometimes insecticide preparations are added to diatomaceous earth to make it more effective. Check the label.

I have used diatomaceous earth directly on a cat. It works but it is not pleasant and can be nasty if your cat breathes in the dust. Imagine putting chalk in your hair. The cat was covered in fleas and it worked to kill them but the cat found it very unpleasant.

Table Salt

Table Salt is sometimes added to diatomaceous earth and to borax to control fleas in carpets and in cracks. Don't put it on the cat directly.

Insect Growth Regulators IGR

Insect growth regulators are substances which disrupt the flea life cycle and stop its development. Ask your vet. Some are sprayed for control of an area, others are intended to be ingested by the animal so that when the flea feeds the blood has the IGR and prevents flea development.

Insect Growth Regulators show a great deal of promise because they are not in themselves very toxic and specifically target a process in flea development. Developers try to identify processes that are unique to the flea and target these processes. This selective targeting can be chitin synthesis inhibitor or substances that interfere with insect hormones. These processes do not exist in mammals and thus the IGR has no effect on them and this makes them safer. They seem to have quite a good track record on cats but are quite toxic to many aquatic creatures. Best to use on pet's bedding than on the animal itself. Here is one brand: Martin's insect growth regulator If you use IGRegulators limit the area because it will hurt beneficial insects as well as pests.

Here is a good article on insect growth regulator.

Insect Growth Regulators for Insect Pest Control a pdf paper by the Imam University Faculty of Agriculture. This is a highly readable article and is not hugely long.

Pest products has a page on IGR available. Many links and names of commercial preparations.

Precor is one brand offered on Amazon. Here is a link to the EPA fact sheet on Methoprene which is the active ingredient.

Insect Growth Regulators for Insect Pest Control a pdf paper by the Imam University Faculty of Agriculture. This is a highly readable article and is not hugely long.

Pest products has a page on IGR available. Many links and names of commercial preparations.

Insect Growth Regulators are sometimes mixed with other insecticides and these can be quite toxic. Make sure that you don't use a combination that is dangerous for your cat.

IGR are sometimes given internally. The inhibitor gets into the bloodstream and when the flea feeds it gets a dose. The flea then passes on the IGR through the poo which gets eaten by larvae, and they cannot develop because of the inhibitor.

Most IGR are intended for application where fleas are found. They are sensitive to degradation and so are not suitable for outside applications.

Fish can be sensitive to Insect Growth Regulators.

Brewers yeast does not work

Brewers yeast has been studied as a possible flea repellent when ingested. It showed no effect whatsoever and so is not recommended.


Equally ineffective is ultrasounds which have been shown to have no effect in EPA and university studies.

Magnetic fields

Magnetic fields have not been shown to be effective.


Vinegar appears to have some effect HOWEVER cats PH is quite critical and adding acid to their water is NOT recommended. It can be used in bathwater if your cat will allow you to bathe him. Alternatively it can be applied with a cloth on the fur, but the cat might lick it off. The vinegar should be diluted. Don't get it in your cat's eyes.


Garlic is toxic to cats and dogs. Do not treat your animals with garlic. It is not effective and it is poison. ASPCA page on garlic toxicity to dogs, cats and horses.

Onions are also toxic to cats and dogs and should not be fed to them.

Foods and medicine that should never be given to a cat. My page on some common things that poison dogs and cats.

Nematodes for flea control

Nematodes are a general name for a little worm. There are many thousands of different nematodes some beneficial some parasitic. THESE nematodes have been chosen because they target fleas. They are used outside in areas infested with fleas. The nematodes are applied and they go to work eating and killing fleas. They are not interested in you or mammals so are perfectly safe to you.

Because they are living, care must be taken to use quickly and not kill them before they can be applied.

Nematodes are not applied to cats directly, only to areas where cats hang out outside.

Nematodes can be sprayed in the yard and help control fleas. They are harmless to pets. 10 Million Flea Killing Beneficial Nematodes - Ecomask - Easy Spray Formula


Flea control in cats is complex because cats are easily poisoned. Best practice starts with keeping your cat healthy and frequent and thorough cleaning of areas frequented by cats. Bathing the cat and vacuuming is an option if the cats will tolerate it. If insecticide is necessary because of the severity of the infestation then a low toxicity insecticide should be used such as pyrithrin. Beware of other substances which are sometimes included. Mechanical Control such as diatomaceous earth is effective but should not be breathed in. Borax, salt and diatomaceous earth can be used in carpets then vacuumed up, but care should be taken not to breathe the dust. Essential oils are tricky and some are very toxic to cats. Never apply them directly on the cat. Only highly diluted solutions should be used near cats. Aromatic herbs are safer, catnip is an effective repellent but does not last very long. Insect Growth Inhibitors are an emerging solution which have been effective and of low toxicity, Nematodes are effective outside.

A final thought, because fleas are potentially health threatening as they can cause anemia, carry parasites and bacteria, a small level of toxic exposure is often better for the cat than a heavy flea infestation with resulting side effects.

Alternative treatments can be as dangerous as regulated flea treatments sold by the vet. Instructions should be followed to the letter.


This article is provided for information only. It is not to be used instead of consulting a VET. If your kitty is sick get some help. Research and information is often contradictory. Read labels carefully for other ingredients included. DO NOT use flea preparations marketed for dogs. Cats are much more sensitive to poisoning than dogs.