Can I DIY rat poison that's safer for other animals?
February 15, 2021 5:36 PM   Subscribe

There are rats in the crawl space under my house. I want them to die. I do not want to poison the food chain so I don't want to use commercial rat poison. Can I make my own? What if I feed them oxycodone? How much oxycodone would it take for a rat to OD and would it be safer for other animals?

Yay, another rat question. I do not want to use commercial rat poison that could poison my dogs or owls or etc. so I'm wondering if I could find something that's toxic to the rats but wouldn't hurt anything that eats them. I have twelve 5mg oxycodone pills leftover from surgery last June (yeah I know, don't hoard drugs, that's not what this is about, please.) If I mush them up in some peanut butter and put them in the crawlspace, would it work? Or would I just be creating addicted zoned out rats who come back for more? Is there anything that will kill rats and nothing else? I also have a lot of dog trazodone (50 mg pills, but several years old) I could part with. Ideally I could chuck drugged peanut butter into the crawl space and they would just gently go to sleep and never wake up.

There is no food outside, no incentive for them to stick around, the trash is secured, there's nothing in the crawl space except ducts and dirt. There's no real way into the crawl space aside from, well, crawling and I am not, repeat not, crawling into a space that has rats in it. I called the two exterminators in my small coastal town; one could get here next week sometime for an assessment and estimate - not to do anything about it - and the other didn't call me back. So I'm on my own here.

They are getting into the crawl space via a vent that is where the gas pipe goes in - they have pried the vents apart enough to get in and out - and I discovered all this when I saw one in my little courtyard. I threw a bunch of moth balls down the vent and down the human crawling access point, which is on the other side of the house. I checked all the other vents; they look fine. I put two snap traps - plastic, Tom Cat, rat sized - by the rat hole. A rat got snapped by both of them on Saturday night and still took 18 hours to die in the rain - until, in fact, my brave friend came over and drowned it in a bucket - and I'm never using snap traps again. Glue traps are similarly out.

I am completely phobic about rodents. I can't deal with live ones at all. I can maybe somehow deal with dead ones if I screw up all my courage. I do have one very brave friend but I can't keep relying on her. I have two large dogs who would probably kill a rat but I'm not shoving them into the crawl space either. I don't want to block up their hole and then give them an incentive to get into the house itself dear gods, so I don't know what to do next. I have ordered an electric rat zapper and it should be here in a couple days but they're not supposed to be outside and outside - in the rain, this is the Oregon coast - is where I need it. Help?
posted by mygothlaundry to Home & Garden (20 answers total) 1 user marked this as a favorite
 
Honestly, I think you should just wait for the exterminator to come in next week—they might be able to help you very soon after the estimate. I don’t think you want to have dead rats in your crawl space either, they’ll rot and stink.
posted by music for skeletons at 5:53 PM on February 15 [18 favorites]


Best answer: I wouldn't mess with diy rat poison. I mean, I might try it f I had the stuff, because I'm well used to dealing with rats. But it sounds potentially as risky as the commercial stuff.

You can try Rat X brand, which is basically really salty rat food, which apparently rats can't handle. Seriously, salt is the active ingredient. That being said, I have had trouble getting rats accepting Rat X. They're serious creatures of habit, so they'll likely be quite wary of any poison at first. Next time I might try mixing it with a bit of peanut butter.

An exterminator will put down traps and/or serious poison. They might make note of places where they have unwanted access for you, and it'll be your responsibility to get those taken care of. Phobias and all, there's no easy way. You're going to have to find a way to handle potentially dead/dying rats.
posted by 2N2222 at 6:04 PM on February 15 [1 favorite]


Best answer: So, pharmaceuticals are actually tested on mice and rats in order to determine what a lethal dose is. They titrate the dose up until 50% are dying, this is called the LD50.

The LD50 for oxycodone (absorbed orally) is 426mg/kg. If your rats are 0.5kg, they will need in the neighborhood of 200mg. So, you probably don't have enough opiates to kill a rat.
posted by floam at 6:10 PM on February 15 [17 favorites]


Best answer: (Of course, even if you had a lethal dose of mostly not metabolized oxycodone in a dead rat, it'd probably also be a lethal dose for a bird that eats the rat.)
posted by floam at 6:14 PM on February 15 [8 favorites]


Ive been battling rats in my attic for a few years, I did try the poison it worked, but it was a bad decision (think: dead rats lost in hot attic), rat traps work, but you have to keep checking them, best thing that currently works for me is the electronic rat trap. little box that works on batteries or plug in, that has a bunch of metal plates, that electrocute rats instantly dead. the best feature is a long led cord that you can hang where you can view that tells you when its zapped one. They even have a newer model that can bluetooth notify you. actually seems like the most humane way to kill a rat.
posted by edman at 6:38 PM on February 15 [12 favorites]


Can you put the electric rat zapper inside the crawl space so it's not outside? Even if it's just by the human entrance so you don't have to crawl in there yourself.
posted by schroedinger at 6:43 PM on February 15 [1 favorite]




Best answer: To answer your more basic question, the challenge with finding a poison that's specific to rats vs say dog is that they're both mammals and share lots of the same vital pathways. Whereas insects and other pests have pathways that diverge more from mammals and so insects are affected by molecules that don't hurt mammals (or as much). Hopefully that's not just a totally obvious answer...

Also rats are pretty big so even though they might need lower doses of things to kill them than humans would, it's probably still enough to kill a small dog or cat.
posted by Tandem Affinity at 7:14 PM on February 15


Best answer: If your crawl space is small and well-enclosed, then you could try sealing exits and gassing them with dry ice.
Kills quickly, no food chain contamination.
posted by Bardolph at 7:38 PM on February 15 [5 favorites]


I have dealt with rats in and under my garage/shop, and I have to say I'm a fan of traps over poison. With a trap, you know exactly where the dead rat is. With poison, they can get into all sorts of nooks and crannies before they die and then decompose.
posted by xedrik at 7:59 PM on February 15 [3 favorites]


You can get enclosed snap traps that, if you‘re really really phobic and don‘t want to deal with it, you can throw the whole thing in the trash without looking at the dead rat. They are pet/bird/kid safe. Here‘s a model I‘ve used — purchase the snap trap separately. Of course the snap trap works better unenclosed but I‘ve made catches with this setup, too.

If you are phobic you do NOT want poison if you can avoid it. It leads to half-dead rats wandering around your property. Not recommended unless you have a very serious infestation.
posted by The Toad at 9:34 PM on February 15 [1 favorite]


Hi there, I'm a toxicologist. I can't say this in my professional role, but I'm more than happy to say it in this context: intentionally setting out substances intended to poison animals is a horrible thing. Feel free to judge that statement, but, again, I'm 40 and have been working in toxicology for almost half my life. Poisons are poisons. They poison living things. They do not care what you intend to poison, they will poison without judgment or differentiation to your intended targets, time frames, or desired level of poisoning completeness. They will maim and hobble and damage, not just kill, living things without attention to your wishes.

If you have the ability to hire an exterminator, you have the ability to tell that exterminator (or a general contractor) that your goal is to prevent intrusion of your unwelcome guests rather than to try to kill the ones that happen to be there now. If the only goal is to kill the ones who are there now, more will fill the niche again and again until you resolve the problem: there's an access point that's wide open. An ounce of prevention is worth a pound of cure.

Whatever approach you choose, please (please) don't put baited pharmaceuticals out into the environment.
posted by late afternoon dreaming hotel at 9:45 PM on February 15 [40 favorites]


Don't do it. Dead rat is going to be MORE troublesome in the crawlspace than live ones.

I bought two Owltra mouse zappers for my house after seeing good results from Mousetrap Monday (I think it was Shawn Green's Youtube channel?). In four weeks, it zapped 4 mice, and there was no more. Either mouse got smarter, or there really are no more mice around here. :)
posted by kschang at 10:01 PM on February 15


Rats are quite a lot less sensitive than other mammals at detecting bitterness. For this reason, denatonium benzoate is often used as a substance that will repel other animals from a rat poison - for example.
posted by rongorongo at 12:39 AM on February 16 [1 favorite]


Best answer: Don't do it. Dead rat is going to be MORE troublesome in the crawlspace than live ones.

I used rat zappers and (professionally-laid) poison. The zappers caught the odd rat but they were a bit temperamental and if some debris crosses the metal contacts and triggers the zap, it drains the battery really fast. Poison was a lot more effective and yes, if the rats are in your crawlspace, and eat poison in your crawlspace, they will likely die in your crawlspace. We found that the smell was usually confined to the one room they were under and went away within a week. It was a price we were willing to pay for rat elimination. Your rat smell may vary.

In the end the one thing that got rid of them was removing their method of ingress to the crawlspace by having the sewer outlet repaired (the u-bend construction that's supposed to stop rats was blocked and they were getting in through the overflow). Get the vent they are using fixed in a way that stops them permanently, or you'll be fighting a never-ending battle against every rat in the neighbourhood.
posted by EndsOfInvention at 1:42 AM on February 16 [2 favorites]


Best answer: Seconding late afternoon dreaming hotel.

Until you hire an exterminator, you could try Messina dog/cat repellent. Even more effective, you could add predator waste. Rats, even in colonies are skittish. This substance gives them the creeps.

As far as I know, it's completely humane. It may not dismantle an entire colony, but it could certainly be partially effective, as well as definitely prevent curious/new rats.
posted by firstdaffodils at 10:08 AM on February 16 [2 favorites]


This answer is going to sound a little farfetched, but I'll list it anyway.

If you block off their entrance, lay coyote waste, and set out saucers of ginger ale or soda(karni mata style करणी माता, of course), the most active or fit rats may become uncomfortable and leave the area.

You could be left with old rats, and some young, who may naturally die out or be an easy dismissal for an ethical-sustainable exterminator.

Rats do not have the ability to process or digest carbonated substances. They become extremely uncomfortable (they can't burp- in some cases, they die-). However, this somehow doesn't prevent them from continuing to drink sweet soda. They'll keep drinking it until it's gone or becomes a serious problem.


The Orkin man suggests soda is a myth- but exotics specialists, techs, and pet owners are specifically taught never to give the animals the substance because it can cause serious problems or death. Data's there 🤷


Good luck!
posted by firstdaffodils at 1:28 PM on February 16 [1 favorite]


Best answer: I've told this story before on here but don't remember where. I was going to have an emerald city party where everything had to be green. Among other things my excellent friend did to help with this was make green agar "jello shots." (I wanted them to be free-standing to look like actual emeralds, and gelatin was too floppy, hence agar.) Friend tried out several different recipes, once leaving the agar "emeralds" out overnight to see whether they'd keep their jewel shapes for the duration of the party. The next morning he discovered that there had been a (f)rat party in his kitchen. I forget how many but I think it was just two or three full agar shots had been consumed entire and the unfortunate rat was lying dead next to the final one, which was barely nibbled. These things were pretty small; like the size of two largish grapes. But most rats are novice drinkers with no tolerance, so it doesn't take much.

In conclusion there is no reason to waste good opioids on rats. Get a bottle of Popov or similar and some delicious sugary mixer and whip up some good strong shooters. It wasn't my friend's aim to kill rats, but it was serendipitous good luck that he made solid shots because the rats didn't tip them over and spill them and thus fail to drink irresponsibly. This might work for you, too! If my friend's experience is anything to go on, they'll continue to chow down steadily until they can't anymore, being passed out, and then presently they will die. They won't be capable of running away to hide, even if that were to occur to them, which it won't because they will be first really happy about the snack and then blind drunk and very shortly after that unconscious and then rapidly dead. So you can just hook 'em out of there and nudge them into a bag and toss them.

(Do not attempt to eat agar shots. They are really lovely and do look like gems, and rats seem to like them, but people not so much. The mouthfeel is horrifying. Nobody at the party would eat them, though a few stuck them on their foreheads and walked around. So that was cool.)
posted by Don Pepino at 2:25 PM on February 16 [11 favorites]


Don Pepino, this answer is officially the best thing I've read on the internet in at least a week. I'm crying laughing.
posted by SinAesthetic at 3:03 PM on February 16 [3 favorites]


Please try the Don Pepino method and report.
posted by firstdaffodils at 7:48 PM on February 16


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