LD50 of Permethrin (orally) in Ball Pythons? (Treating prey for mites)

I’m looking to see if anyone has seen any data on the LD50 for permethrin given orally to ball pythons?

I was able to find some studies done on brown tree snakes, which for ingestion was in the range of 20-40mg/kg. But, I wasn’t able to find anything for Ball Pythons.

For background, I’m dealing with an outbreak of tropical rat mites, and I want to (if possible) understand the level of risk my treatments of the rodents will place on my snakes in the future.


I have had a similar problem once myself and was recommended to cull the colony rather than take the risk of using as feeders. This was many years ago, sorta pre-internet, and I therefore had to trust my vet. Not sure how I’d deal with it now…

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Once my rat breeder’s employees sprayed the rodents on loading day. All the adult ball pythons quickly regurgitated but seemed fine. I think I did loose a few babies. Supposedly would have been fine if they had waited maybe a week.

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I’m putting culling the colony at the bottom of my treatment possibilities. Setting aside the cost and pain of losing so many animals, and the pain of dealing with bringing in frozen and live to cover feedings while things start back up; I also am very fond of a number of them, especially the rats some of which have names, and very pleased with some of the results of the ASF line breeding I’ve been doing for many years.

I found there are a good number of treatments that all look to be very effective against the mites, and all with different levels of risk to them. Cross checking those against what is understood for risk levels for the Ball Pythons is where things get a bit more difficult.
This seems especially true when I’m moving from say skin/fur contact of the rodents with Permethrin into that rodent with some Permethrin on it now being ingested by the snake. From what I have seen, Permethrin seems to tolerated to some level when applied to a snake, but I’ve not been able to find anything with levels of ingestion, or the real ability for the snake’s liver to clear the Permethrin from the body. I would love to just use the Brown Tree Snakes numbers, but I worry that, that would be like applying the numbers from dogs for cats, which we give you a lot of dying cats.
And to add a little more completeness, I’m looking at using the same treatment that was used in clearing up some lab infestations of Tropical Rat Mites, with cotton balls impregnated with permethrin.
Following their treatment, it appears they added 60-90mg of dried Permethrin to the rodents environment, of which a small percentage would be transferred to the rodents (maybe .6-.9g?). Add to this, since Permethrin doesn’t seem to break down on it’s own without something effecting it like sunlight, I can’t simply run half life numbers to roughly understand a time when it won’t exist on them.

Here is a link to one of a couple of similar articles I found on this treatment:

I figured I would add this here incase anyone searching finds this thread one day:

I have decided against introducing the permethrin cotton balls for now. I’ve gone with the following to try to slowly eradicate them with a lot larger safety margin (over the unknown) and a bit more work:

I’ve treated the rim and the lip with permethrin, an area the mites have to travel to get into or out of the tub, and an area the rodents have near zero contact with. (Everyone is in a FB rack) Treatment was with 0.5% permethrin wiped onto the rim and lip with a cotton ball, three times, while allowed to dry in-between applications (~10 minutes). This was done outside to protect all animals and people from the vapor.

With fresh tubs, a small amount of bedding was added (~1") , and about 1/8th of a cup of food grade DE (Diatomaceous Earth) was sprinkled on top. These tubs were swapped with the currently infested ones, all cage extras were either soaked in hot water with a little Dawn in it for about 30 minutes, baked in the oven for 30 min at about 150-170ish, or tossed. Both the baking and the soaking seemed to kill all mites visually (and checked with a 10x scope).

Following this, there were no more mites visible on the outside of the tubs, and a large number of dead mites on the rim. Inside the tubs all the rodents seem content, though there is a fair number of mites visible in the bedding which detached from themselves after the transfer.

I’m currently running a air purifier to try to keep the dust levels (from the DE) down, but given that they are in tubs, and close to the bedding, I’m not sure how much it will help protect them. I’m keeping a close eye out for any level of distress. I’m waiting to see how effective the DE is at killing the mites in the bottom of the tub to evaluate if it’s helpful.

The next steps will be to start switching out tubs every 3 days, and attempt to isolate then remove all remaining mites without giving them a chance to reproduce. As it appears the Tropical Rat Mites are similar to Snake Mites, in that they have decent periods of time detached, including during egg laying, I’m hopeful that 60 days, this issue will be resolved.

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I’ve used ivermectin orally on my rodents for nearly a decade with no side effects for the snakes. Intensive process but it’s knocked out both internal and external parasites on the rats for me.


That’s good to hear, ivermectin was actually next on my list if this fails. For those that were to become feeders, did you stop feeding them to the snakes for a period of time after treating them?

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10 day wait period is all I do.

For treatment; give each adult rat a dollop of ivermectin horse worming paste, that is slightly smaller than a grain of rice. For juvenile rats use half as much. Repeat the process three times at seven day intervals. So three total treatments over 21 days. It is much easier to do with someone to hold the rat and someone to dose it. Ivermectin does not generally work well in suspension so this is the only way I found without having a veterinarian come out.

Edit to add: the only side effect that I saw commonly, is profuse sweating which can also be indicative of you overdosing the animal. Mortality rate has always been inconsequential. Occasionally after treatment cycle, I will lose one or two rats, typically older animals.


I have seen on YouTube and heard of breeders also putting Diatomaceous Earth in a sprayer with water and spray directly on the rats and cages, both to limit the dust and to stick better to the rat. May want to look into it, this is secondhand info, but looked interesting and non harmful to the rats. I have personally used ivermectin, like @ballornothing but instead of paste I got sheep dredge liquid and I only treated the adults at, I think - .5ml (the smallest liquid syringe you can get, first line) weekly for 4 weeks with good results. These were not feeders, they were my stepdaughters pets, so I am glad that @ballornothing confirmed the safety of use in feeders! Good luck! Whether it’s reptile mites or rodent, I truly can’t stand them-


I’ll fully admit that I’m still feeling my way through the best way to use the DE. My best understanding is that the DE acts as small knife edges that cut the mites shell as they walk through it and they then dry out. I have found that it sprinkled under the rack has managed to catch and kill tons of the mites, and that’s all dry powder. The area of DE that got wet under there doesn’t seem to be doing anything. I’ll have to do some more research on applying wet to the rodents.
Since you mentioned snake mites, I have to say having now dealt with both, the rodent mites are MUCH more painful to deal with, literally, they bite me, my wife, the dogs, and leave little painful, itchy, red welts. So far, we have thousands of dead mites and had a couple days now without bites on us, so that’s a good sign so far.
After seeing the great success of having the rim and lip treated with permethrin, I’m tempted to do that to all my snake tubs as well, especially my isolation racks. It looks to be an extremely effective way to isolate any outbreak to only that snakes tub, or ones they have been in contact with though them or their cage furnishings.


I am glad you are making some progress on the rat mites! As far as snake mites go, I know it’s dangerous to apply to the snake directly or even put a snake in the quarantine cage/bin before it totally disperses but I always had success with the prevent a mite spray. Nasty stuff I know but when applied as directed and just to the enclosure works great! As far as the snake, I like the old water with a couple drops of dawn treatment, totally safe for the snake. I haven’t had to deal with multiple snake or enclosures outbreak though, so treating a individual snake is much easier to manage and monitor. That’s why I always do a 10-12 week long quarantine, assuming they have mites and proactively doing a soak test and treating the quarantine tub.

It sounds like we are on exactly the same page. I also treated snake mites with repeated dawn and water “treatments” and really liked it. In part it was easy because the girl who had them was isolated and I only had to treat here. I’m not sure how I would feel if I was treating a rack of 30 snakes.
Provent-a-mite is chemically and concentrationly identical to what I’m treating the bin rim and lips with. After watching how effective it is at isolating the mites to inside each individual bin instead of crawling everywhere, and with only the rim and lip treaded to boot, I’m a believer.

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And pictures for all, rim and DE with their accumulated mites, and some of the mites seeming living happily in the tubs sprinkled with DE.

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Thanks for the pics! It looks like a good sized infestation to me! I am sure that DE is safe for the rats for sure, but don’t know how effective it is at completely eradicating them. Which is why your multiple type approach is a great idea! You may even want to go a step further and start ivermectin treatments, just to try to help protect the rats from getting re infested quickly. I would follow @ballornothing advice on the dosage and type, since he has had experience with his feeders before. Probably the safest way to go, at least for the adults. I would try to separate or freeze off a lot(if possible)of the young non breeders just to get your numbers down and be safer if you do administer ivermectin. Keep us updated, this is definitely a interesting and helpful post for all rodent breeders/owners!