How Long Can Head Lice Live Off The Human Host?

By HelloLife

Lice - the pest we all wish we didn't have to know. When an infestation strikes the game is on. We'll do all we can to get them out of our hair and out of our house! But how can we be sure they're gone for good?

First, we need to understand the life cycle of the louse.

1. The Nit Stage:

Day: from the laying of the egg to about 6 days after.
Appearance: A very small off-white oval less than a millimeter in size at their largest and only about a 1/3rd of a millimeter when laid. Dead eggs are brown and collapses on the side. Many people mistake head lice at this stage for dandruff. The easiest way to tell which is which? Dandruff is easily removed - nits are not.
"Nit" is the term for the egg state of a head louse. Nits are laid at the bottom of the hair shaft (within 6 millimeters for warmer climates, closer in cooler climate) in order To get the body heat they require for proper incubation, the female louse will lay her nits at the bottom of a hair shaft with natural type of glue she emits to help them stay in place.

2. Nit Hatching Stage:

Day: Between 7 and 9 days from when egg was laid.
Appearance: The head of the louse begins to emerge from the egg. Eggs that have the louse has already hatched from are pale, hollow with a hole on top and won't pop when squashed.

Once it has emerged fully, it will no longer be considered a nit.

3. 1st Instar(Insect Development Stage)Head Lice Nympth Stage:

Day: Between 8 and 9 days from when egg was laid.
Appearance: The louse now looks like an insect but is still very small. They are compared to the size of a pin's head with the females being a bit larger than the male. Their body is yellowish to rust depending on how recently they fed.

This is the most precarious stage for a head louse. For one reason or another, the grand majority of lice die during this stage of life. Should they survive for three more days however, they will shed their exoskeleton and enter the...

4. 2nd Instar Head Lice Nympth Stage:

Day: Between 11 and 12 days from when the egg was laid.
Appearance: As you might imagine, a 2nd instar head lice nympth looks quite similar to the 1st instar head lice nympth, only a bit larger.

5. Final Molt - Adult Stage

Day: Between 16 and 18 days from when the egg was laid.
Appearance: Like those in the previous stage only larger yet.

Adult lice are active and they can move quick. This is the stage at which reproduction and egg laying begins. In this time, the female can lay up to 90 eggs (nits).

6. Death

Day: Between 32 and 35 days from when the egg was laid.
Appearance: How can you tell if a louse is dead? Remember they are typically quick and active. If you poke them and they don't move, they're dead.

Of course, all of this only really applies to head lice living in their ideal environment, next to their feeding source, in our hair.

How do head lice leave the hair?

Contrary to popular belief, head lice do not fly or even jump, yet they can end up off the head and around our homes.

With the heat of our body, they have a hard time telling the difference between our hair and the fibers of the hat we were wearing, or the blankets, pillow of carpet we were resting our head on. While we are in contact with these things, they may move off our head in search of a meal and be left behind.

How long can head lice live off the human host?

Most often, head lice are spread through physical contact (if their heads touch or are close together) and by sharing clothing, hats, or scarves. (Pets do not get lice and do not spread them.)

However, assuming they leave the scalp and do not find another host, or are not able to find their way back to their original host, a head louse will typically starve within 1 to 2 days. Nits can live off the host longer, but rarely become separated, as the female louse "glues" the nit to the hair strand. Nits often look like dandruff because of this, but unlike dandruff, cannot easily be brushed out of the hair.

How can I prevent the displaced head lice in my home from reinfesting?

While it's not likely that lice will live for long in your home, there is still a risk of lice spreading from one person to another.

When a head lice infestation strikes don't panic, but don't delay in treatment either. Take care of your head lice in the hair immediately, and be sure to wash anything the infested person may have come in contact with.

Use hot water and a lice treatment on all:

Bedding
Pillows
Blankets
Towels
Clothing that may have come in contact
Combs
Brushes
Hair Decorations and Hair Ties

Vacuum the furniture and car just in case.

Head lice, while a nuisance, are NOT a sign of uncleanliness or dirtiness. Anyone can contract head lice. If you or your child has head lice, don't spend time worrying about how you got it, just work on solving the problem!

Sources:
http://www.idph.state.il.us/public/hb/hblice.htm
http://blogs.webmd.com/all-ears/2006/09/lice-not-so-nice.html
http://schoolipm.ifas.ufl.edu/tp2.htm
http://www.holdfast.sa.gov.au/page.aspx?u=798

Photo Credit:

Eran Finkle, Mick E. Talbot

29 Comments

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HelloLife Guest
thank you for this i had to show my friend about lice! thank you ever so much.
Commented on HelloLife April 19 2009 at 12:12 am
HelloLife Guest
My daughter has lice. I thought it was dry scalp like she gets every year this time in the fall. I have cats and seem them scratching, treated them for flees. With her persistent itch and not seeing anything I treated her anyway with RidX. Four days later, my Nanny sees them crawling on her head. I was mortified.. The school nurse told me "if her kids ever had them she would burn down her house".
What I learned? Heat! It is said to kill more of louses and 90% of the eggs with just 1 blow dry. Using RidX and then conditioner, I combed through her hair and still found live louses.. this why she was still so bad in 5 days. I am going to repeat in 4 more days , but with washing everyday followed by blow drying (said to be 50% better than anything including RidX on the market). I then will comb. I am also washing her sheets ever day for the next 3 weeks and vacuuming the same. They live 2-3 days so this is more a precaution for me. The first sign of lice by the way is a rash on the back of neck and behind of ears. We had that.
Commented on HelloLife September 30 2009 at 8:16 pm
HelloLife Guest
My question is that i havent had lice for over a year and i have this suitcase and theres two blankets in them and journals and i just received from my parents who may or may not have alice but i know the home is. but i want to know how long can they live off the blankets in the cold outside? and can they jump off a suitcase to me? and can they live off journals? and how long can they really feed off the blankets before finally dying??? please and thank!! =]
Commented on HelloLife November 19 2009 at 6:04 pm
HelloLife Guest
Hello, I hope someone can answer this for me. I read that heat will kill the lice and KILL EGGS as well. Is this true, and if it is than after treating the hair and blowdrying it I was thinking of useing a strightener (it gets really hot)all throught my daughters head. Do u think this would kill any live ones that are left and all the eggs? the reason i ask is I have treated her twice now and i found 1 live one and sonme more eggs.
Commented on HelloLife February 26 2010 at 10:13 pm
HelloLife Guest
Cut the single pieces of hair out!!Why take a chance after all that work!Good Luck!
Commented on HelloLife April 05 2010 at 10:04 pm
HelloLife
Amy,
Try Licenex shampoo on her head - it washes away lice and nits (eggs) with enzymes - the enzyme can dissolve the outer protective coating of the lice then comb through the hair with a nit comb. One treatment might be enough
but this is not a shampoo with harsh chemicals - but it does the job.
Commented on HelloLife April 26 2010 at 3:21 pm
HelloLife Guest
ok my friend has lice i just noticed and she slept over at my house so she has been in my room under my bead and has been all over my room and cloths that i wear and has been all in my house so just wondering if sence she has been in my room and under my bed wich had my close under it is the lice in her hair going to be in my room like under my bed and in my room and house and slept on my couch in my livingroom and sat on a chair in my livingroom plzzz idont want lice i never had it!! plzz answer as soon as possable plzz!!! im really young and scared!!!
Commented on HelloLife July 02 2010 at 11:50 pm
HelloLife
Destiny,
There is a shampoo called Licenex that washes away lice and nits (Eggs). Wash everything with this soap and check for living lice or nits = use a nit comb on your hair. All is not lost just be methodical.
Commented on HelloLife July 21 2010 at 2:56 pm
HelloLife Guest
I Really Need Help..!!!!!!
like i had lice two years aqo cuz i found one in my hair..
and my mom been washing my hair like every week now and then most of the times i hear and feel things in my hair like i think i still have lice. But how could it possibly be still in my hair after two years!!!
i told my mom my hair is so itchy she just says my hair needs to be washed WHAT SHOULD I DO PLZ I KEEP SCRATCHING MY EARS AND HAIR SO BAD
Commented on HelloLife July 30 2010 at 5:01 pm
HelloLife Guest
Like is there any other way to get rid of them without having to buy rid and stuff like that in the stores
Commented on HelloLife July 30 2010 at 5:08 pm
HelloLife Guest
umm actually rhey do jump, they just dont fly, hope that tells you something
Commented on HelloLife August 21 2010 at 5:15 am
HelloLife Guest
Hi Christina im so sorry to hear about your problem.I have also had head lice and am still trying to get rid of them all.The best way to get rid of them is to follow these steps:
1: With an adult cover your hair with a solution made from Tea Tree oil and water (you can put it in a spray bottle)
place a shower cap over your hair this will sufficate the lice.
2: After half an hour rememove the shower cap and cover your hair with conditioner.
3: Use a fine tooth comb (you can purchase a lice comb from your local pharmacy) and comb through your hair in sections.
4: The lice will get trapped in the tooth of the comb.
5: Have a bucket of boiling water near by so you can rinse out the comb. You will find heaps of lice (bugs) and nits (eggs) in the water.
6: After combing through your hair thoroughly wash your hair as normal. Repeat this process everyday for 7 to 10 days. And then as a precoutionary method wash and condition your hair everyday using the lice comb.
This has worked for me Good Luck !
For more info visit Wikipidia.
Commented on HelloLife August 25 2010 at 5:37 am
HelloLife Guest
oh ma qosh thank u
Commented on HelloLife September 05 2010 at 3:31 pm
HelloLife
Hi Christina,

You could probably kill lice with permanent solution, but we would not recommend it. Try natural methods, like tea tree oil, before using harsh synthetics.
Commented on HelloLife September 08 2010 at 10:30 am
HelloLife Guest
ok thank u
Commented on HelloLife September 08 2010 at 5:31 pm
HelloLife
One other thing, Gail. You might find the following article interesting:

http://www.hellolife.net/explore/head-lice/can-i-get-head-lice-from-the-beauty-salon/

Thanks for reading!
Commented on HelloLife October 19 2010 at 3:04 pm
HelloLife Guest
Actually, thats a myth, head lice actually prefer clean hair, over dirty hair, its easier for them to breed and the nits to stick to the hair. Often times, if you use hair product in your hair it reduces or prevents them from sticking with you. My son just got lice from his preschool. Its a pain in the butt, but not the end of the world. I shaved his head down and washed and picked thru his hair killing what I find and hot washed the linens and clothing.
Commented on HelloLife November 19 2010 at 11:49 am
patti
hello all...my niece continues to get lice seems we get rid of it only for it to come right back ...mind you she has beautiful locks of curls and it takes hours to comb thru with a nit comb but im the only one she will allow to do it...not real sure why it keeps returning...any insight??? i treated her head on sunday and planning to repeat weekend hoping it goes away...best advice i can give is if you have a child in school or daycare and they start itching check the head immediately...
Commented on HelloLife October 20 2011 at 10:31 pm
Lucy
I shampoo my daughters hair every morning with tea tree shampoo - the lice are repelled by the smell. I have also heard that conditioner makes the hair shaft to slippery for the eggs to stick - not sure if this is true but worth a try if you are having continual problems.
Commented on HelloLife November 29 2011 at 3:48 am
Melissa
My daughter currently has head lice and it has been a challenge but nothing no parent can't handle. Here are some helpful facts to help you erase some of the myths heard.

Lice prefer both clean and dirty hair, it makes no difference. Clean hair allows the lice to move more easily among the hair strand while dirty hair allows for faster breeding. Lice does not equal poor parenting, anyone can get it.

Those who have gotten it repeatedly back to to back need to make sure that they are checking the enitre family for lice. If you rid your child of lice but then another household member has it, all you are doing is transfereing the lice back and forth. Only the person(s) infected needs to be treated, the other family members should be checked daily just to make sure they do not have it.

Head lice happens to be the second most common condition among children and 80 percent of schools across the country have at least one outbreak per year. LIke I said before, anyone can get it.

Lice cannot jump or fly, they can only crawl. When scratching the head, they can be flung, causing the appearance of jumping.

Head lice can only live for 24 hours when away from a human host. They cannot live in pillows, sofas, or any other surface for any longer than a 24 hour window.

All lice do not die immediately after lice treatment. It often takes several hours so it is recommend going through with a lice comb two hours after the treatment. By doing so, you increase your chances of removing all of the lice.

Last but not least, more than one treatment needs to be done on the hair to kill any newly hatched lice.
Commented on HelloLife December 09 2011 at 11:43 am
Connor
Thanks very much for the article, it was interesting!

I've also found some good information on http://www.vosenekids.co.uk/headlice-knowledge/

It still makes me chuckle when people believe that head lice can jump from head to head.

All the best!
Commented on HelloLife January 04 at 7:44 am
Billie
Hi,
I manage a pest control company and get questions about lice all the time. It usually takes 48 hours for a louse to die without a blood meal (feeding). Heat will kill lice and eggs but it has to be over 125 degrees. You can wash items but it's really drying that kills the lice. I would suggest a steam cleaner on furniture that you sit on frequently. If someone is constantly getting reinfested, it could be a child or friend at day care. My son got lice from his girlfriend, no one else in the house ended up with them, but I used the rite-aid brand lice shampoo and that did the trick. I also washed and dried his bedding on high heat. My eight, six, and one year old never ended up getting lice from their brother (Thank God).
One other thing, I would suggest sending a garbage bag to school with your child so they can place their coat and other items inside it. It will help prevent lice spreading to their items.

Commented on HelloLife January 05 at 10:14 am
Shannon
My daughter got lice in Grade 9! I thought this was strange until she told me her friend who had slept over had it. That friend has a younger sister. So you see how easy it is to "spread the love". I got her hair all cleaned up and did one last check (one week after the second shampoo) and found nothing. I took her for a hair cut, her ends were so damaged from the shampoo. The hairdresser saw nothing as well. That night, with perfectly clean hair she had another sleepover with that same friend. Last night, one week after the sleepover, there was lice in her hair. Urrrgh! Back to the washing, picking routine again!!!
Commented on HelloLife January 13 at 6:10 am
Cheyenne
I have had lice a couple of times, and the over the counter and perscribed stuff never worked for me.
What we learned is that dying my hair has always done the trick.
Also remember to spray down your car seets!
Commented on HelloLife January 31 at 11:28 pm
kathy
Dawn dishwashing liquid (twice) then conditioner, works every time
Commented on HelloLife February 14 at 10:15 pm
Wanda
hello everyone

at my daughter school theres so many kids with head lice...come out to be that my daughter didnt get it first check around next thing u kno they rechecked her again n there she goes with the lil eggs..im so discusted by this ughhh..i even get sick to my stomach ...i treated her w the shampoon n myself just in case n so far no eggs or nothing ...but last nite i checked her new pillow i sprayed rubbing alcohol n a few lices came out the pillow case ..omg i almost died!!! yuckkk...thats wha really i dont understand how is it possible she didnt have it on her hair after or before just had the lil eggs n w the treatment n removing it with the comb we havent seen anything...but then again she had lice on her pillow how can this be possible??? could have an egg fell on the bed n hatched there..right now i have her room locked with alcohol n clorox all over ...i dont kno wha to do :(
Commented on HelloLife March 17 at 10:30 am
sprouty
Hi Wanda. You've got to be sure to wash all bedding on hot and dry on high if possible. Also a good idea to shampoo any furniture she may have rest her head on.
Commented on HelloLife March 19 at 8:09 am
Maria
My mind was enlightened after i read this blog thank you so much!
Commented on HelloLife April 01 at 5:22 am
Dawn
I would like to know how far apart hangers should be in a area that coats are hung (public area) to prevent sharing stuff like head lice, scabies, and other contagious skin rashes.
Commented on HelloLife May 01 at 10:18 am