Sciencemadness Discussion Board

Exterminating voles (burrowing rodent)

Fulmen - 28-7-2025 at 13:15

So a friend has a major problem with voles. Unfortunately they have recently banned the use of poisonous gas, so nobody sells calcium carbide anymore.

Regular rat poison is ineffective as the get enough vitamin K through their diet to be fairly immune. That really only leaves traps which is a major undertaking, so I'm tasked with finding a better approach. Regular poisons are out of the question as it could kill their cats or contaminate the soil.

My best suggestion so far (other than a continued search for carbide) is motor exhaust, which should be doable albeit a bit equipment intensive in the long run.

Chlorine from bleach might also be an option. Perhaps a bit cumbersome, especially if you need to cover multiple entrances, but it's simple, low cost and OTC.

Another interesting approach would be a pyrotechnic gas generator of sorts, but it needs to be "clean" in the sense that it won't leave any dangerous ash or byproducts. Tall order, I know. But this is Sciencemadness, if anyone can come up with a solution it's you guys.

yobbo II - 28-7-2025 at 13:48

CO cartridges were tried for badgers.

Made fron Na Nitrate and charcoal.

https://digitalcommons.usu.edu/wdmconference/1993/all1993/30...

Yob

Fulmen - 28-7-2025 at 14:32

Good find, it lead me to this:
https://www.aphis.usda.gov/sites/default/files/8-gas-cartrid...

Dr.Bob - 28-7-2025 at 15:36

My favorite solution to most problems is explosives. Anyone else here see the Red Green Show. Or Bill Murrey and the gopher...

Fulmen - 28-7-2025 at 17:10

Agreed. But sadly there are burrows next to the house foundation, so I expect that solution to be rejected.

This looks like a hoot: https://www.youtube.com/watch?v=CgztUzqaL3E

[Edited on 29-7-25 by Fulmen]

bariumbromate - 28-7-2025 at 20:16

put about 17g of calcium hypochlorite (super shock pool chem) powder in the entrance hole, then pour 311ml of hcl down the hole on top of the calcium hypochlorite, it will generate a lot of chlorine that will flood the hole and kill the voles, after that RUN.

EDIT: make sure that everyone leaves the area and it's not too windy or it will blow all the chlorine out and kill you ;)

[Edited on 29-7-2025 by bariumbromate]

Fulmen - 29-7-2025 at 01:46

The USDA document posted earlier lists two compositions:
1:
Sodium nitrate 53%
Charcoal 28%
Fullers earth and Borax 19%

2:
Sodium nitrate 50%
Charcoal 9%
Sulfur 38%
Undisclosed 3%

The second one seems to be most common for gophers and smaller rodents and should be quite simple to make.

@bariumbromate: That's another approach that should work. Unfortunately calcium hypochlorite isn't common around here, I can only find cyanuric acid based products.

shadowflare - 29-7-2025 at 10:22

everyone here giving reasonable/boring responses so i'll propose something else:
i think it would be absolutely hilarious if sticking a garden hose into one of their burrows does the trick. that method definitely has my vote.

the more boring but effective method (outside of explosive or traps) would be carbon monoxide, its used pretty commonly on even professional extermination. some people have mentioned using car exhaust, which back before modern epa regulations would have produced. for making it i recommend filling a can up with charcoal, a hole on either end, and forcing air through it with heat gun, hair drier, ,vacuum, whatever. a paint can with press fit lid works quite well. alternatively you could dig a hole next to the burrow and cover it, digging out small channels for airflow into the burrow with the input being at the bottom. monoxide smells slightly sweet, if theres enough to smell you're already breathing in unsafe amounts so abort. you become noseblind scarily quick too so pay close attention.

Fulmen - 29-7-2025 at 11:06

Water is supposedly not very effective, apparently they build their nests with that in mind. But I suppose enough of anything will cause havoc.

Another candidate that deserves consideration is H2S. Simple to make (iron sulfide and HCl) and toxic as heck.

chempyre235 - 29-7-2025 at 12:02

I don't know where you are, but zinc phosphide pellets are available in the US for moles and voles. These could be used directly or acidified to PH3 gas, though the pellets are only 2% phosphide by weight. Surely ammonium salts could work reasonably well instead of phosphide, or perhaps by the heating of urea with base.

Alternatively, I used to see strychnine for the same purpose, though I haven't seen it on store shelves for the last couple of years.

Twospoons - 29-7-2025 at 14:15

I've euthanised rats from a live capture trap using DCM. Rat in a box with a little dcm on a tissue makes them woozy in 30sec, unconscious in 1 minute and dead with 5min. You might be able to adapt that to flooding the vole burrow with DCM vapor.
The MSDS I read says DCM is metabolised into carbon monoxide in the body.

CuriousOnlooker - 29-7-2025 at 15:49

Maybe there's a youth in the neighbourhood who has ferrets that could be sent down after them?

Fulmen - 30-7-2025 at 02:02

If zinc phosphide was available we wouldn't be having this discussion. But aluminum sulfide should produce H2S in contact with water, and that shouldn't be too hard to make.

There is even a entry in the wiki:
https://www.sciencemadness.org/smwiki/index.php/Aluminium_su...

[Edited on 30-7-25 by Fulmen]

Radiums Lab - 30-7-2025 at 09:39

In our area they use NaF as rat poison.

Fulmen - 30-7-2025 at 09:48

That'll work, but regular poisons are out of the question as it's a vegetable garden and they have cats. I'm going to try the second sulfur-based smoke bomb first, if that doesn't do the trick I'll explore aluminum sulfide.

BromicAcid - 31-7-2025 at 13:58

There is an article here:

https://pubs.acs.org/doi/10.1021/ie50136a024

It was written in 1921 so shortly after WWI and the author is trying to figure out what to do with the abundance of phosgene remaining after the war. The conclusion of the article, which covers discovering a good solvent for phosgene, is this:
Quote:
The imagination allows of possibilities of practical uses for such solutions in ridding lawns, etc., of moles, and in "mopping up" rats and other vermin.


Interestingly, just looking at the numbers,phosphine is an order of magnitude more toxic than phosgene when comparing the LD50's. But to me it just seems over-the-moon nuts to do this (no, I am not advocating that anyone do this, I just thought it was a funny article but then I went down the rabbit hole of the LD50).

bariumbromate - 31-7-2025 at 23:57

don't do hydrogen sulfide. it will stay in the ground and the garden will stink for months, my fume hood still smells after 1 year ago i made H2S

Fulmen - 1-8-2025 at 10:05

Oh, that doesn't sound good. Guess I'll have to do some field tests far away from people first if I want to explore that approach. Thanks for the warning.

bnull - 1-8-2025 at 17:18

There was some research about inducing a sort of hibernation in small animals with the help of hydrogen sulfide (see, for example, Potential applications of hydrogen sulfide-induced suspended animation). Imagine this, you try to wipe the voles out of your garden but they come back some time later, as if they had taken a few days off.

Are repellents out of question?

yobbo II - 2-8-2025 at 04:00


Another one I have heard (on this board) that is used for rats is ClO2. Generated from Na Chlorate and acid.
It is explosive at high concentrations so you would need to keep the concentrations low.

Yob

[Edited on 2-8-2025 by yobbo II]

Fulmen - 2-8-2025 at 04:57

@bnull:
No, anything that isn't dangerous to cats or poisons the soil is of interest. I'm looking at this with a two-prong approach. First chemical warfare to get rid of the infestation, then they need to make the area less appealing to the vermin to prevent a repeat.

I did try the "Giant Destroyer" (with sulfur) mix today, but it wouldn't ignite at all. I suspect the sodium nitrate was too wet, I'll make another batch with potassium nitrate to see if that solves the issue.

[Edited on 2-8-25 by Fulmen]

charley1957 - 3-8-2025 at 04:58

I’m not even sure what a vole is, but I’ve had trouble with gophers in the past. I have tried engine exhaust for hours and hours, I’ve tried flooding, I’ve tried waiting and shooting them. My best results came from just digging out the tunnel and setting traps. Once I caught the gopher, I stuffed his dead body back down into the tunnel and filled it all back in. I haven’t had a gopher now in six or seven years.

CuriousOnlooker - 4-8-2025 at 06:02

Quote: Originally posted by charley1957  
I’m not even sure what a vole is, but I’ve had trouble with gophers in the past. I have tried engine exhaust for hours and hours, I’ve tried flooding, I’ve tried waiting and shooting them. My best results came from just digging out the tunnel and setting traps. Once I caught the gopher, I stuffed his dead body back down into the tunnel and filled it all back in. I haven’t had a gopher now in six or seven years.

Sounds like the simplest, and effective.

Fulmen - 4-8-2025 at 10:38

The new formula worked much better, igniting easily and produces copious amounts of thick sulfur-rich smoke. I'm going to make up a 10-pack to see if it has any effect.

Charley: Voles (link in the original post) are about the size of rats. Digging out the tunnels isn't viable unless you feel like digging up an entire field, these suckers are numerous. And it's not like we're ever going to exterminate them, but we need to downsize the population significantly. A friend of them recently lost 1500 apple trees, so this isn't a minor nuisance.

Of course chemical warfare is just the first step, a long term solution will include repellents and other ways of making the area less habitable. Putting up more owl nest boxes is also something that is being considered.

pesco - 31-1-2026 at 08:49

You could try urinating into the burrows (easy for piss-takers :D) and then pour some bleach on it.
Chloramines are pretty nasty and might do the job.

One problem I can foresee is that if enough of explosive NCl3 is generated then some voles might become airborne, thus more difficult to control ... :D

pesco - 31-1-2026 at 08:56

Another, enviromentally friendly way us to introduce strict diet for cats.
Once Whiskas becomes scarce, voles should start disappearing

pesco - 31-1-2026 at 10:18

Now on a serious note.

Couple years ago my backyard got overrun by rats.
Roughly same time I found dead young rat next to pepper plant. Some 15-20cm away. Leaves have been nibbled on. I knew that Solanaceae are poisonous, but didn't expect tat they are so potent.

Over next couple weeks I was crushing some leaves in a mortar, mixing the paste with peanut butter or spreading on cheddar and placing in various places around the garden.
Within month ot two rats ave disappeared. Never found dead fox and none of neighbourhood cats disappeared.
That doesn't mean it won't kill a scavenger. There is a potential. Looks loke young leaves are most potent.



Same time warning - if you have veggie plot with peppers/tomatoes/potatoes and little kids please make they do not munch on leaves/flowers/young fruit of geese plants!