I always assumed that a joint “butt” is called a roach because of it’s appearance. It’s small, brown and kind of shiny and therefore bears a striking resemblance to a cockroach.
Link to column: What’s the origin of the word roach… – CKDH
No offense to Mikeee, but in Fear and Loathing in Las Vegas Hunter Thompson claims to have attended a seminar for police officers where an instructor said that the term “roach” derives from the resemblance of a marijuana cigarette to a cockroach. On hearing this, Thompson’s Samoan friend turns to him and observes that the person who thinks there is a resemblance must be really stoned.
Then again, I don’t have a better explanation, although it does occur to me that Roach is an Irish surname, so the possibility suggests itself that the term may originally have been coined in reference to some specific person.
Welcome to the Straight Dope Message Boards, Mikeee, glad to have you with us.
When you start a thread, it’s helpful to other readers if you provide a link to the column that you’re discussing. Yes, it’s on the Home Page now, but in a few days it will vanish into the vast morass of Archives. The link helps others to find what Cecil had to say (and thus understand your comments on it) more readily.
Funny how impressions differ. In my life I have, sadly, seen more cockroaches than doobies, but I’ve seen both, and far from there being a “striking resemblance”, I wouldn’t have said there was any at all.
I think the resemblence increases, the more you smoke.
Here’s a link for any future readers:
Origin of Roach, Joint and Stoned
As for ‘stoned’ I can offer some wild/irresponsible conjecture.
I always imagined that the word ‘stoned’ described that sinking feeling you gets in your head and the really heavy feeling (like a stone) of your body when you’re so ‘stoned’ you’re about to nod off -or so I’ve heard 
You guys listen to the new guy. I smoked dope (also called “boo”) with “beatnics” in the early 60’s. Joints that had been smoked down were often allowed to go out, then were put behind the matches in a book of paper matches. Roaches, the bugs, hide behind stuff like calendars and if you smack the calendar, you flatten some bugs. When you took the butt out from behind the matches, it looked a lot like the flattened bug. Generally we’d re-roll 3 or 4 roaches to make another joint.
Man, them were the days. Took 2 or 3 fat ones (joints) to cop a buzz. We used to actually hide, doors locked and shades drawn, before we’d toke.
Life is good.
This information presented for historical purposes only. Sneck. Eeeyrr.
Mikeee’s no newby. (S)He’s been around for a long while. I haven’t seen any posts lately, but I remember the name.
Ok, buddy, what’s up with that, huh? Somebody call the feds.
Martin Booth states in Cannabis: A History that the term roach comes from the Mexican folk song “La Cucaracha” (The Cockroach), which tells the story of one of Pancho Villa’s foot soldiers, who were colloquially known as “cockroaches” and who smoked marijuana to relax and to prepare for battle.
A verse:
It’s catchier in Spanish.
Everything’s catchier in Spanish ;), but I don’t buy that etymology.
& here i thought ‘cucaracha’ was a nickname for a rattly vehicle… was i the victim of a bowdlerised version of the song?
…ya no puede caminar
porque le falta, porque no tiene
gasolina que quemar
See
I poised the question to the pros over at the American Dialect Society Mailing List.
The cucaracha theory has some merit, according to them. Not that you can find an actual link between the Pancho Villa time and the 1938 Harlem quote, but it’s not out of reason.
Man, you can find everything on this site.
Anything except the true origin of the term “roach” for a partially smoked marijuana cigarette. Note that it’s always partially smoked. Mexicans don’t, or at least didn’t back in the day, call it a roach. Smoked or not. I seem to recall a name that sounds something like “fraho”, but don’t hold me to that.
A partially smoked joint is called a roach because it looks like a squished cockroach. That would be the “german” cockroach. The little tan one.
You buy their books, you send them to school, and what do they do?
They listen to the likes of Cecil. 
Rode with Pancho Villa, did we, mangeorge? :rolleyes:
Your knowledge of what Mexicans, or Americans for that matter, called a joint or a used butt of a joint between 1895 and 1938 is suspect, as you weren’t there. And you haven’t supplied what they called it.
You could still be right. But just an unfounded suspicion as of now.
Ok, ok now, i’ ll tell y’all. cockaroach, was a term used to describe a pot head. a smoker of marijuana, it was described in the 1800’s that this devil weed caused overwhelming addiction, rape, murder, insanity and perversion in users.( much like the phenom of alchohol today) the user was described as a ‘cockroach’ because of that behavior in Mexico. there were reports of suicide and homocide related to use and anyone seen using was subject to immediate arrest. their behavior was seen as akin to roaches, hiding and running from sight, hence active at night. perhaps if you found evidence of their use you would find a stub of a ciggarette, and think " a roach", i.e. a scummy pot head was just in the area. search arizona press, under history of mexican in the southwest. 1800-1900’s.
Where’s my reply? My witty repartee from last night? I’m sure I posted a response to samclem’s expression of doubt concerning my knowledge about the origin of this use of the word “roach”.
I’ll summarize;
Didn’t ride with Villa in Mexico, did walk with Chavez in Wasco.
Don’t know why you limit me to the years between 1895 and 1938.
I got the story, as I related above, from folks, older dudes, who were in the middle of the “action” as the use of the term was gaining in popularity.
I have common sense, anthropological authority, and Mikeee on my side.
What else is commonly called by the slang term for the people who used it?
Booze, for the folks from boozia?
Smack, from the Smackian Islands?
Butt, for the Buttanians.
C’mon. Use your branes.
rezwar. You’re the one asserting that the terms were used in the late 1800’s-early 1900’s. YOU find the cite. We’ll be eternally grateful, and I’ll see that you get credit in the Oxford English Dictionary, Merriam-Webster, and will shout your name from the rooftops as a scholar. Good luck.
mangeorge. What some old geezers told you in the '60’s was no more nor no less than what THEY had probbly heard from some geezers older than themselves years before. But that don’t make it true.
You “hear” all kinds of things. You “hear” that Bill Gates is gonna send you money.
Find me a cite before 1938 for the term “roach” to mean anything to do with marijuana.
Again, you could be right about the cockroach look-alike story.