Book lice or bed bug nymphs? How to tell the difference

by nobugsonme on March 4, 2008 · 25 comments

in not a bed bug, photos

This is a book louse (psocid), submitted for ID in the forums. Many bedbuggers have mistaken book lice for bed bug nymphs. Notice the shape of the body is elongated, with three clear segments. There’s a pronounced head.

book lice

Compare this photo from L. Sorkin and R. Mercurio of a bed bug nymph:

bed bug nymphs

Both book lice and bed bug nymphs are light colored but bed bug nymphs have a less elongated body. Bed bug nymphs don’t look like they have a neck, whereas book lice do. Bed bug nymphs are clear but will become red when they have fed.

If you find a book louse, don’t worry — they are common in homes and don’t usually pose a problem. Despite the “louse” in the name, they don’t have anything to do with species that feed on humans. If you want to learn more about psocids including book lice, here’s a fact sheet from the University of Minnesota: Psocids in Homes, by Jeffrey Hahn and Steven Kells.

Many thanks to the user who shared the book louse photo, and gave us permission to use it here.

Updated 8/2016

1 lieutenantdan March 5, 2008 at 10:42 am

What I would like to point out to the newly infested is that when you start to inspect your house you may see booklice, everyone pretty much has some. To really see some details in these bugs you need 10x magnification and that is limited that is how small these creatures are so it is very easy to assume that they may be bed bug nymps especially to the new people or untrained eye. This one I found on my mattress encasement last week which I though at first was a spec of dirt. When I went to collect it it slowly moved so I caught it with tape and took a loupe to it and of course I freaked a little. I was pretty positive that it was not a bed bug but because it is so tiny I could not be 100%. I scanned the bug and sent it to a friend who is an entomologist and immediately she told me that it was a booklouse.
You can imagine how relieved I felt.

I stress the importance of collecting samples ( entomologists hate the samples on tape)
and send them to a professional to verification. Booklice are not parasites they feed on mold and books. Universities usually have a team of specialists to deal with these creatures to reduce the numbers as to help preserve important paper documents.
So beware of the Booklouse.

2 nobugsonme March 5, 2008 at 9:59 pm

Thanks for the photo, Dan!

3 aballen June 2, 2008 at 11:09 am

Well, well, well. I did as suggested here and had my so-called BB which were id’d by at least 5 different PCO’s which ended up costing me thousands in throwing out items, hotels, medical bills, and months of psychological torture. My pests are BOOKLICE!!! All this time! My first entomologist id’d psosids which look nothing like these booklice. I imagine there are many species though. I’m off to the find out about booklice and biting mites now. If anyone has any ideas about biting mites or how to rid my home of booklice, please respond. My new PCO id’s this immediately, so I will stick with that company, ACE out of Cincinnati.

4 vacationer June 2, 2008 at 5:09 pm

Yes, I found booklice in my place too. Put ’em in alcohol, got them under 20x, and spent a very nervous hour hunting the web for pix until I found what they were. They looked awfully like real lice. There are some good photos out there online. (I also found other tiny bugs like museum beetle larvae and springtails.)
They’re tiny as heck. Get your bugs into alcohol so they’ll die, be preserved, and their ID can be checked with strong magnification.
– v.

5 nobugsonme June 3, 2008 at 8:24 pm


From what I understand, booklice (despite the name) are not a problem in most cases. They do not bite. So I am confused why you are asking for advice about biting mites?

6 nobugsonme June 9, 2008 at 2:28 pm

More psocid photos from UESbugs here and here.

7 Am June 25, 2008 at 12:20 pm

Today I finally found and caught a bedbug using scotch tape. It was a fed 2nd stage larva –

Tried taking a photo of it but my camera’s macro isn’t powerful enough. It looks exactly like in the picture linked above, at 2 mm and with a red bloated stomach (guess who’s blood).

It has been exceedingly difficult for me to find bedbugs. I have been waking up with itchy huge red welts on and off for a few years now, but each time, an inspection of my bed, sheets and etc yielded nothing – no signs of an infestation – poo, bloodstains and such. Also, as I mention, I don’t always get bitten – maybe once or twice every month or so. Any idea why?

8 nobugsonme June 25, 2008 at 10:55 pm

Here are some possibilities:

It may be that you do not react to every single bite. We really don’t know enough about how bed bug bites affect people, but we know some folks don’t react at all, others have terrible reactions, and some people seem to react sometimes more than others.

Another possibility: you may have been bitten once or twice a month somewhere else (workplace, friend’s, relative’s, etc.) And now you have brought at least one home.

I am sure there are other possible scenarios.

Here’s my concern: if you get bitten a few times a month at home, and you definitely found a 2nd instar, this suggests that bed bug nymphs are being born. If there’s at least one egg-laying female, as there probably is, then it will only get worse.

I would get the home treated. Verify it’s a bed bug (some pests can be mistaken for these) and get someone in to treat.

Finally, if you have further questions or need support, please come to the forums! You will get more replies there:

…or click the blue button top right.

9 Liz July 4, 2008 at 12:16 am

I need help. I noticed two bites under my arm, on my back on a wed. Then got about three more daily for about 3-4 more days. The same with my daughter. Her bites are not so bad but mine are red, tender and red and irritated around the bite. My husband and 2) other daughters seem to be fine. With the exception of 2-4 mysterious bites on my 1)year old, but not the swelling and such as mine. I’ve racked my brain to figure out what could have bit me because I have not noticed any bugs on or in the house out of the ordinary. And my family and I never get bit like this in the house. All I can figure is bed bugs coming home with me from a hotel I recently stayed in. I stayed on a weekend, came home Sun. and started noticing bad bites wed. Now a week later, no new bites. I’m terrified of bed bugs. I have since gotten bit by a mosquito and seen a flea in the house (I think a family of stray cats could have brought them by because they hung around our porch for days). My bites from the flea and mosquito don’t swell like the other bites. How do I know for sure that I have bed bugs???? And what should I do now before they multiply???



10 nobugsonme July 4, 2008 at 12:35 am


It is possible you brought bed bugs home (from a hotel, or frankly, from anywhere else you’ve been), but it is also possible you are reacting to flea bites.

Read the three top FAQS which provide basic information and key dos and don’ts:

You should also read the FAQS which help you learn how to identify bed bugs and their signs. Unfortunately, if you have only been bitten for a week, and don’t have many bites, you may have a small infestation (which is good of course–that it’s small, but it may be hard for you or a PCO to detect bed bugs or their signs).

Learn to inspect and do inspect, carefully. Check each bedroom and the sofa/living room area. Remember people who are not getting “bites” may be bitten and not react. Bed bugs could be where they sleep or sit too.

Start by inspecting your luggage that you took to the hotel. Get a flashlight and go over every inch of it and inside pockets. There’s a CBC video in the LINKS section (see top menubar) which shows you how to search a hotel room, and the techniques will work in your bedroom too.

If you see any signs of bed bugs, preserve them (ie don’t clean them away!) and get a PCO in to see them and to treat at once.

If you see NO signs, you should consider following the suggestions in the FAQs for dealing with recently worn clothing and bedlinens on the beds. IF it is a bug or two, you MAY just get them this way. Make sure items are sealed in bags before being washed and dried on hot. Don’t move items about the house which are not sealed in an airtight fashion, or you may spread bed bugs. Don’t change where anyone sleeps.

If after bedclothes are laundered (and hopefully this will be ASAP), you still are being bitten, get a PCO in. They should rule out other problems (fleas) and if they cannot find bed bugs they will either tell you you need visible evidence, or treat anyway. (PCOs differ on this.)

I do think it’s important to try and identify the source is definitely bed bugs. But it’s also true that recent infestations can be hard to detect.

If you want further advice or support, please go to the forums:

11 tony August 20, 2008 at 7:23 pm

Hi, I have found book lice or psocids in my basement. It has been unoccupied for many years and has had carpet on the basement floor slab. The walls have about 60-90 % humidity in them but when I made a hole in the wall the wall was dry and the fiberglass pink was also dry. The carpet was removed and there is glue stuck to the floor that cannot be removed. The walls had wallpaper and I removed most of it. Now I know that if I reduce the humidity level, I remove the carpet and the wallpaper that these book lice will most likely not thrive. However, it is time to renovate my basement and I am worried that once the subfloor is done and the walls are painted that these book lice will come again. We have seen them on walls, in books and on some clothing. I do not know how to get rid of this problem, and I am worried to apply insecticides since I have small children that will be playing in the basement. What do you recommend? Can these book lice resurface? What temperature and humidity level do they need to survive in? If I redo my basement floor and walls what materials and procedure do you recommend so as to avoid these book lice from reemerging, especially because they like organic glues to eat on? I am confused and need help and no one seems to have a clear cut answer. I am worried that they will resurface and I will have to redo my whole basement all over again a second time. I also fear that if I do opt for insecticides that they will not be effective and that these book lice will later on in the future resurface? I am at the point of paranoia and do not know what to do, what can you suggest?

12 nobugsonme August 20, 2008 at 11:39 pm

Hi tony,

I only know about bed bugs, unfortunately. We include book lice/psocids here so our readers can see a pest which people sometimes mistake for bed bug nymphs.

If you leave a post in the forums, a professional may answer your question.

Otherwise, I would recommend getting a pest control professional in. They should be able to safely treat your home in the presence of children.

13 fedup1 October 20, 2008 at 9:45 pm

I just had an exterminator come into my apartment to treat bed bugs for three treaments. The bed bugs ruin my daughter’s skin. Now them things are back in high gear. we do not have more money for the exterminator. MY TWO YEAR OLD DAUGHTER is getting BIT!!!! We need advice how do get this problem gone before the holidays before we have more guest come into our apartment.

14 nobugsonme October 21, 2008 at 1:07 pm


If you live in a home that’s attached to other homes (apartment, row house, etc.) then they may be coming from your neighbors, who will need a careful inspection and treatment if infested.

If neighbors have bed bugs and remain untreated, it will be very difficult if not impossible for you to get rid of your problem.

When a pest control pro is not able to get rid of bed bugs in 3 visits, it suggests either
a) the PCO you used may not have a lot of experience treating bed bugs successfully, OR
b) the neighbors may be infested and untreated or insufficiently treated, OR
c) you are possibly being reinfested via some source, OR
d) some combination of the above.
There may be other explanations. It’s important to follow your PCO’s instructions carefully.

Unfortunately, they are hard to treat. Your best bet is a pro. who has experience with bed bugs. If you rent, your landlord may be liable to pay.

In any case, you may get more suggestions in our forums and I encourage you to post there:

15 bill January 31, 2009 at 2:11 am

The booklice that bite people have wings on the back and come from Mexico. These also have beaks. Bill

16 Ugo February 12, 2009 at 5:38 am

Hi folks,
when collecting samples to give us a great place to keep them is a small prescription drug bottle.
Please no tape!

17 nicole March 25, 2009 at 7:00 pm

Ive notice a bump here and there on my arm leg and toe and it made my husband and i icth so bad we didnt think anything but maybe it could me a mosquito until we sat down and thought about it and said its not weather for that right now then we started seeing these bugs that i never seen before then i was told that my neighbor had bed bugs so now we are bugging out i then went on ling hire an bed bug specilist to come to my home and after we still seeing then then we threw out our couches seen one or two but killed them so now its been almost two weeks havent seen anything yet and they sealed up all our cracks and holes in the apartment do u think they are still here and is outlandlord surpose to pay up back for our furtinure

18 nobugsonme March 26, 2009 at 12:12 am

Hi nicole,

I don’t know where you live, but it is unlikely the law makes landlords pay to replace discarded furniture. Some landlords might help tenants with this, but I have not heard of anywhere where they had to.

Most bed bug cases take multiple treatments, spaced about two weeks apart. You have to keep getting treatment until the bed bugs are completely gone. They need to treat ALL the apartments that have bed bugs, at the same time. And they need to keep coming back until the problem is gone.

If you have more questions, please post them in our forums:

You will get more responses there.

19 adrian August 1, 2009 at 10:04 pm

omg please please help i was very itchy in my pubes area and when i scratched in my nails there was this tiny very small insect looking thing i went to the doctor i thought they were crabs he said they wernt now that i started payin attention to where i see this very small tiny clear things ive notice that i have them almost evrywhere ive notice them on my shoulder on my chin on my neck even on my face i dont know what it could be i dont get out a lot so i dont know where i could have gotten this i dont even know what it is and im the only one in my family that seems to have this im scared i dont want to tell my mom cause last time it was a big deal and it was not crabs i thought it was not crabs since i havent done it i cant afford to go to the doctor again so please please help me they look clear very very small and it looks like they have this tiny tiny anteneas in the front or the back i dont know its two tiny antenas in the front please help me

20 nobugsonme August 1, 2009 at 11:52 pm

Hi Adrian,

It does not sound like bed bugs to me. Only unfed bed bug nymphs are
clear; when they feed, they turn red. It would be unusual to see only nymphs and for none of them to feed when they have had access to you.

What I suggest is that you get some clear packing tape and when you see one, pick it up on the tape. You can even tape it down on an index card.

If it is a human parasite that lives on you (like body lice), a doctor will be able to diagnose and treat it.

If it is a pest (like some kind of mite), a pest pro will be able to get rid of it.

Either way, you do not have to live with this problem.

21 Buganoia September 23, 2009 at 1:38 pm

Although I haven’t found any actual bedbugs, I’m still fearful because I’ve been having itchy skin and sometimes accompanying red splotches periodically for the past month since I moved into my new apartment. My landlord sent me an exterminator, who said I didn’t have bedbugs and joked that I was paranoid (thanks!) but he didn’t look very hard (just at and around the bed), so I’m afraid it wasn’t quite enough reassurance to dispel my paranoia. I bought some of the Climbup Insect Interceptors to try to catch any new bedbugs infestations. While I still haven’t found any big, adult looking bedbugs, I DID yesterday find a couple of psocid-looking bugs in one of the Climbups. I trapped him in a folded piece of tape and looked at him under my magnifying glass. He looks like other psocids I’ve seen before (in my old apartment), but it looks like there is a dark spot in the middle of his belly. This made me wonder if maybe I was wrong and he was actually a bedbug nymph. I know trapped in a folded piece of tape isn’t an entomologist’s preferred way to look at an insect, but can I still take it to someone to get a second opinion? And where can I go in New York to see someone who REALLY knows the difference between the types of bugs and wont’ misdiagnose me? Advice?

22 Buganoia September 23, 2009 at 1:47 pm

I should clarify:
By Psocid I mean Book Lice . .. they’re the same thing or at least very similar, right?
And I found about 3 of them in one of the Climbup Interceptors. Two of them were dead, but the third was wandering around and couldn’t get out, so he’s the one I caught in tape. I want a professional to look at it, but I don’t know where to go. I live in Manhattan.
Any help is much appreciated!

23 Danny June 29, 2010 at 11:26 pm

How do bed bugs travel and how long between when eggs are layed and they hatch and do they look the same as babies?

24 William July 11, 2010 at 2:06 pm

All the p0sted comments sound very familiar to my own experiences and all are horror stories. I moved into a rental apt in Oshawa, On., & was told there had been no problems with bugs etc by the landlord so I moved in. Within a week I had begun itching all over and soon after began seeing an insect I couldn’t identify so I caught a bunch, put them into a container & did some research on-line. I was shocked at what I was dealing with & called my landlord. After several conversations he accused me of bringing them into the building and threatened me. I had to throw out a brand new queen size bed & sofa and had to spend hundreds to get all my clothes washed at the coin laundry & other clothes drycleaned. My apt was fumigated but not before my girlfriend’s townhouse became infested as well. I am now forced to sue my landdord & supposedly have the right to according to the Landlord Tenant Board Act . The immediate financial cost has caused me extreme hardship & has severely strained my relationship with my ex-spouse & son because they will no longer let me in their house for fear of me bringing in more bed bugs into their home. I am not confident that I will win my courtcase either because apparently this kind of case hasn’t been tested enough in court & the outcome could go either way. It appears that in a very short amount of time that this problem that has plagued me has ruined my life in more ways than one. No more “sweet dreams, and don’t let the bed bugs bite.” I spend my nights in a state of near paranoia, trying to fight off these blood sucking parisites to no avail & no matter how diligent I am there seems to be no end in sight to them.

OK then, perhaps someone who is in the same boat as I, can let me know if there is any kind of a happy ending to what seems to be a perpetual nightmare? I am definitely at my wits end with all of this. Thanks, Will….

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