How Pubic Lice suck (your blood)

crab louse
A pubic louse, or crab louse

I became an unwilling expert on pubic lice a couple years ago when I bought “crabs” online at the request of a reporter. Really. It’s a long story, and you can listen to a version of it here; the abridged version is someone calling himself “Lice Lice Baby” claimed he would sell you “Giant Japanese Pubic Lice” as pets.  He re-branded his crab lice as “Seamonkeys in your Pants.”

The French call pubic lice “papillon d’amour”, but for all the happy euphemistic talk about “the ultimate sharing of your love,” crab lice are blood-sucking parasites. At the time, my primary concern was pointing out that deliberately infesting yourself with pubic lice was probably not a very good idea, and a public health risk.

This somehow made me the go-to person online for pubic lice, which is not, frankly, an expertise I particularly aspired to.  I was talking to someone recently about public lice (now a regular occurrence) and I realized that I didn’t know the specific mechanism by which pubic lice suck (aside from the fairly obvious suckage of being infested). I did a little research, and what I found out actually made pubic lice creepier. I did not think that was possible.

One of my primary resources was a paper with this wonderful title:

BURNS D.A. & SIMS T.A. (1988). A closer look at Pthirus pubis, British Journal of Dermatology, 118 (4) 497-503. DOI:

A closer look, indeed! This is a scanning electron micrograph of the sucking end of a crab louse, magnified about 1000 times.

pube lice haustellum

Pthirus pubis is a member of the Order Anoplura or ‘sucking lice’. It is a solenophage (vessel feeder—from the Greek ‘pipe’ + ‘eating’), introducing its mouthparts directly into a blood vessel to withdraw blood. The components of the mouthparts responsible for probing the skin and piercing a blood vessel are kept withdrawn within the head unless the insect is feeding… In the front of the head is a small, snout-like tube, the haustellum, which is soft, eversible, and armed with teeth. Figure 5 shows the haustellum retracted, and the buccal teeth are clearly visible.

But wait! There’s more!

When the louse is about to feed… the buccal teeth rotate outwards. The teeth cut into the epidermis [skin] with a movement compared to that of a rotary saw, and the haustellum is gradually driven into the dermis. It eventually comes to rest with the buccal teeth fully everted, anchoring the mouthparts in the skin….The stylets are advanced into the dermis as a single bundle and probe for a small blood vessel. Once the stylet bundle has pierced a blood vessel feeding begins.  [emphasis mine]

electron micrograph of crab liceEgad.  That little tube? It’s like a hypodermic needle going into one of your blood vessels.

If you haven’t already unconsciously crossed your legs while reading this, this next bit should do the trick. One of the characteristic signs of pubic lice feeding is little blue spots on the skin. It’s a combination of blood leaking out after that mouth-needle is withdrawn and a reaction to the saliva of the louse.  Another symptom of a crab louse infestation is described as “black powder in your underwear.”  That powder is your dried up blood, after the louse has digested it and pooped it out.

I’m not sure that anyone besides me really needed to know this information, but it is a fascinating example of how insect mouth parts have evolved to make them highly successful external parasites!

Related Posts:

I have pubic lice in my mailbox

As much as that sounds like a euphemism, it isn’t.

Remember the crazy guy who claims he has specially bred giant Japanese crab lice that don’t bite? And that they make great pets? (“Like Sea Monkeys in Your Pants!”)

So, when I wrote about that–and how utterly full of shit that website is–I got an email from a reporter. The website offers to send you your very own “pets” if you send them your address and a buck. The reporter wanted to buy some lice and have me look at them.

I thought the site was just a creative ad-farm scheme, so said “Sure! Send ’em to me!”
Because, seriously.
It had to be a a scam. Who is going to go to the Better Business Bureau and complain that they didn’t get the pubic lice they paid for?

Just in case, though, I gave him my home address, rather than my work address, since I have only been in my new job 7 months and wasn’t sure what might show up in the mailroom.

And then: An envelope DID show up. (Sealed with duct tape, too!)

It appears to have a postal mark from Teterboro, NJ. And scrawled across the front: “Live Insects! Handle with Care!”

Inside was a folded letter, and inside the letter was this:

I think most of you are having the same reaction I did: EW.

The letter that came with it had instructions:

I think I can safely speak for the vast majority of the readers of this blog when I say “Oh, HELL no!”

I’ll wait while the mass collective shuddering dies down.

So–I put the “specimen” in a sealed tupperware container with a moist towel, set it on my plant warming pad (since lice are triggered to emerge by moisture and heat), and took them to work with me the next day. Where 2 graduate students were fascinated, and 1 was pretty much traumatized by the whole concept and probably tried to autoclave herself after I left the lab.

[Also, a tip: if you walk into your new workplace brandishing a container of putative pubic lice and sand, you may want to provide a more detailed back story than “I bought them on the internet.” Just some advice.]

Anyway, we looked carefully under the scope, and aside from documenting that Mr. LoveBugz is (a) brunette; and (b) has pubic hair that is very smooth and well conditioned; we found no nits or lice.

There was sand; and there was some stuff that looked like seed capsules; but unless lice have developed egg capsules that look remarkably like they have cell walls, there were no nits, dead or alive.

Here’s the closest thing to a nit I found (additional photos here and here.) Nothing that I have read in any taxonomic descriptions so far mentions this kind of pattern.

While plant cells have cell walls, no animal cells do. Ergo: This ain’t an animal.
Everything I picked out of that sample turned out to look very similar–plant material, not animal.

There are regrettably few photos of crab lice nits available online, although plenty exist for head lice. You can see some sculpturing of the outer egg case in this photo, but nothing like…well, cell walls. You don’t see it in this electron micrograph, either.

There was a hole in the envelope, so it is entirely possible that the nits that were promised fell out of the envelope in transit. However, why in the world would you not send them in a sealed container of some kind? Even a paper towel in an unsealed Baggie™ would have worked.

And why mail them in sand? Sand is abrasive, and likely to crush anything else during transit in surface mail. Sending the lice packed in sand, and telling the recipient to put sand in their undies and not wash for a week?
Yeah, that’ll happen.

Conclusion: The Site is Still Bullshit.
But they are willing to go a long way to keep up their hoax and/or delusion.

EDITED TO ADD: Some folks are arguing that I haven’t “proven” that the site is BS. Extraordinary claims require extraordinary evidence. They claim to have lice that don’t drink blood and aren’t irritating–which contradicts what we know about all 3 types of human body lice for recorded history, as well as physical evidence for an even long period of time.

They have provided no additional evidence for me to evaluate that claim, and in fact set things up so it would fail. I stick with my conclusion.

Additional things to read about pubic lice: