Feeding Your Reptiles: Frozen/Thawed Rats and Mice

One of the first questions that comes up whenever I tell people that I have pet snakes is inevitably, “what do you feed them?”  People are incredibly curious about how snakes eat, what they eat, and where you get such things.  And many people reveal during these conversations that the only reason they’d never looked seriously into getting a snake as a pet was because of a fear of (or simple distaste for) the idea of feeding live prey.

Most people are a bit surprised when I tell them that I simply buy frozen mice or rats, usually in bulk (packages of 12 or 24) so that I don’t need to worry about going to the pet store every single week.  I can then thaw the prey items out, one at a time, much like you’d thaw out a chicken breast before cooking it.  It’s fast, easy, and convenient.  And my snakes get a good meal whenever they need it, without me having to trek across town to the pet store, or worry about keeping live rodents in my apartment.

 

So Why Frozen/Thawed Instead of Live Prey?

There are people who make the argument that live prey is more “natural”, because a snake in the wild has to stalk and kill its prey.  I find such arguments to be patently ridiculous, because there’s really nothing “natural” about keeping a snake in a glass enclosure in your home.  Most snakes in the pet trade were captive-bred — they’ve spent their lives living in “unnatural” conditions — and many were selectively bred for traits that would get them killed in the wild (ie, albinism).  Snakes in the wild rarely live for more than a few years, while in captivity they can live for decades.  Perhaps a frozen/thawed mouse is a bit unnatural, but it’s certainly no more unnatural than feeding kibbles or canned food to your cat or dog.

Many shops that carry reptile products do offer live prey items as an option, but any argument that a live mouse is somehow “healthier” or contains “more nutritional value” than a frozen one is purely specious — if anything, the frozen prey will be healthier, because pet stores often don’t have very good housing conditions for their prey items, don’t properly feed them, and don’t monitor for health problems the way that a dedicated rodent production facility has to do.  Live prey items might also carry parasites picked up at the store (or elsewhere), which freezing will kill off — live prey items are a potential source of mite infestations, for example, or may contain parasites in their guts.

The biggest risk with live prey, of course, is that it might fight back.  Rodents have long, sharp teeth that can seriously injure your beloved snake-friend.  A snake that misses on the first strike, or gets a bad grip on its prey, can be severely bitten (even killed) by a cornered, fighting-for-its-life rodent.  Vet bills for reptiles get expensive quickly — since they’re an “exotic” pet, even walking in to the vet’s office or emergency clinic with them can be a $100 appointment fee, before any tests/surgeries/medicines/etc even enter the picture.  And many vets are untrained in reptile care, and will be able to do little to help your injured friend — especially if you’re going to an emergency clinic or the like.  Herpetological specialists are rare, and their offices may have limited hours.

 

What If My Snake Doesn’t Like Already-Dead Food?

There are instances where a snake doesn’t immediately take to eating things that have been pre-killed for it.  Wild-caught individuals (which you should never buy — animals taken from their natural habitats are usually illegal and have to be smuggled across borders, are typically less healthy, and you may be destroying natural ecosystems by participating in their sale), or animals who were raised on live prey in captivity (there are still some major breeders out there who feed live, despite the risks), may not immediately recognize a frozen/thawed rodent as a food item.

There’s the odd animal who will simply never take to eating frozen/thawed, especially if this type of prey was not introduced to them until they were an adult.  But in 99% of cases, a bit of care and attention will get your animal eating f/t prey.  A few tricks to try, if you’ve got a fussy eater on your hands — I’ll arrange them from least to most macabre:

• Warm the prey item to approximately body temperature by immersing it in hot water until it feels warm to the touch.
• Wiggle the prey item around in front of the snake’s face (you may want to use tongs or forceps, rather than just holding the prey item in your hand — it’s not unheard of for a snake to mistake a human hand for a yummy rat, especially if you’ve got rat-smell all over your fingers).
• Cut the prey item open a little bit, to get a stronger “blood” smell for attracting the snake.  Anecdotally, puncturing or crushing the skull is the best way to do this (apparently brains smell delicious), but if you’re squeamish it may be better to go for a less-gruesome tactic.
• Try purchasing a live prey item, but killing it just before feeding it to your snake.  I’ve seen various YouTube demonstrations of how to use vinegar & baking soda to make a CO2 chamber at home, or how to use CO2 cartridges for the same purpose, but such DIY creations tend to be unreliable — often the prey simply falls asleep, and doesn’t actually die.  And there’s an argument to be made that suffocation may not be particularly kind, even if it looks (from an outside perspective) like just falling asleep.  If you’re not terribly squeamish, snapping the spine is one of the most humane & painless ways to euthanize a rodent.  If you feel confident in your ability to do so, snapping the neck manually is the most precise and “gentle” method.  Many people teach to simply whack the rodent (hard) off a table or other hard surface, which is less precise and may only stun the prey item, not actually kill it … plus it just looks & feels fairly brutal.  My chosen method (because I hate feeling bones snapping in my hand) is to place a hard, thin object like a screwdriver over the rodent’s neck, hold the tail in my off hand and the screwdriver in my dominant hand, and push (sharply) down and forwards.  It’s fast and precise, and the prey item feels little-to-no fear or pain, because it all happens in less than a second.  I don’t like doing it, but I’m pragmatic enough to understand that this is still far less traumatic to the animal than being dropped into a tank with a live snake, and then bitten & squeezed to death, would be.  Always wear gloves when handling live rodents; they have big teeth and can deliver mean bites.

If absolutely none of the above suggestions work, and your snake has gone a long time without eating, you may have to resort to live prey.  If that’s the case, feeding smaller prey items with greater frequency is usually the way to go.  A snake that could eat a medium-sized rat twice a month, for example, might do better if fed rat pups, every single week.  Younger/smaller prey items are less likely to be able to fight back or inflict serious injuries on your snake.  Never feed live prey without supervising the feeding process (have a set of good, thick gloves on so that you can pick up a struggling rat or snake should things go badly), and be aware of risks like parasites — check incoming live prey thoroughly to be sure it’s not carrying mites or the like, and always check your snake out visually following a feeding to look for bite or scratch injuries.

 

Are There Any Risks With Frozen/Thawed?

Now that I’ve outlined how f/t is the safer and more humane way to go, I’ll go over the couple of risks that may come along with feeding frozen prey items.

Most important is making sure that the prey item is thoroughly defrosted.  Snakes are cold-blooded.  A prey item that feels warm to the touch, but still has a big chunk of frozen meat inside of it?  That could cause your snake’s internal temperature to drop enough to cause serious problems, or even death from organ failure.  The same is true if the prey becomes too warm (which is why you should NEVER use a microwave to defrost frozen prey — the internal organs of the prey item will heat much faster than the outside, and can get hot enough to cause burns).  The microwave also risks actually cooking the meat, and snakes don’t have the same biology that we do — their bodies aren’t designed to digest cooked meat.  Defrosting a frozen prey item is best done by immersing it in hot water and leaving it to sit until it’s thoroughly thawed out (the larger the prey item, the longer it needs).  Give the prey item a squeeze, to make sure there’s no big frozen parts inside.  If it still feels cold to the touch, it’s not ready yet.

The other risk (which isn’t really limited to f/t items, but is more of a concern because they’re probably being stored in your freezer alongside your own food) is transmission of any rodent-borne dirt/bacteria to your own food & utensils.  Keeping separate “snake utensils” is recommended — a set of tongs & a “defrosting bowl” that are for snake-related uses only.  Frozen rodents are unlikely to have any parasites or diseases still living on them, since most bacteria and viruses and the like can’t live at freezer temperatures, but double-bagging frozen rats/mice & being sure to wash your hands after handling is a useful “just in case” measure.  Double-bagging also helps to prevent freezer burn, and may help to disguise the bag of frozen rats from any friends/family who happen to open your freezer and peek inside (I’ve definitely had friends scream and drop glassware upon going into my freezer to grab the bottle of vodka I keep in the freezer door, because the other shelf in the freezer door is the “rat shelf” … several broken glasses later, I’ve learned to warn people of this in advance).

 

Costs and Additional Notes

Snakes are extremely low-maintenance pets.  Being cold-blooded, they only need to eat a fraction of the amount that a warm-blooded mammal or bird would — and (generally) the larger the prey they eat, the less often you need to feed them.

Here in Southern Ontario, small “pinky” or “fuzzy” mice cost about $1-$1.50 apiece, while adult mice may be $2-3.  Medium-Large rats may be more in the $5 to $8 range.  If you’ve got an especially large animal, you may need to be feeding a larger prey item like rabbits, which can cost $15-20 depending on availability in your area … but on the plus side, such larger animals often only need to eat once a month or so.  Buying in bulk can get you discounts, but you need to have freezer space for storing 24 or 50 or 100 prey items in order to make such discounts a viable option — and remember that like with all food, there’s a limited amount of time that something can be kept in the freezer before freezer burn starts to set in & nutritional value is lost.  Airtight storage bags & a clean freezer without frost on the walls will help with longevity in storage.

If you’re getting a new snake, ask the breeder/store/rescue where you’re acquiring it if it’s already eating frozen/thawed prey.  If not, be prepared that you might have to spend some time teaching your new pet to take f/t, and be ready to potentially buy some live rodents & kill them yourself, to get things started.  If that doesn’t seem like something you’re prepared for, ask for another animal that’s already taking f/t, or ask if they’d be willing to “test” the animal on f/t food for you, before you commit to buying/adopting.

And if you really love the idea of having a pet snake, but really *can’t* stomach the idea of handling dead mice/rats, there are a few species out there that eat other foods — like eggs or fish.  Dasypeltis, an African breed, is a commonly known egg-eating colubrid snake which you may be able to get your hands on (although they’re much less common than other colubrid species in the pet trade, and finding a captive-bred specimen may be challenging) — they are usually fed quail eggs in captivity.  Many species of garter snake prefer to eat fish (although live feeder-fish carry high risk of parasites; do your research before deciding on a fish-eating snake as a pet, and you may want to go frozen/thawed with fishy feeders, too, to kill off any parasites).  Other colubrid snakes may eat eggs, fish, or earthworms — but they may require vitamin or calcium supplements added to their diet, as these foods are not as nutritionally valuable as mammal prey.  Thorough research is necessary before acquiring any pet — don’t simply trust what “some guy at the pet store” said.  There are myths out there about snakes eating insectivorous diets and the like — these are MYTHS, and a snake won’t get proper nutrition eating only bugs.  But if you’ve done your research well, a non-rodent-eating snake may be a very beautiful and rewarding pet choice.

Feeding Your Reptiles: Mealworms

One of the main reasons why many people resist the idea of keeping reptiles as pets is the food requirements.  With a cat or dog you can just buy your food at the store or the vet’s office (or if you’re really fussy, cook a special diet for them out of foods that you would probably eat yourself).  With reptiles, though, there are insects and even mice and rats to consider as food items.  These “creepy-crawlies” can definitely be a turn-off to some people, and while there are some vegetarian reptiles out there (Mali Uromastyx are becoming very popular these days), they’re not as easy to find as the more common geckos and beardies — and choosing a pet based on diet really does limit your options.

When things really get difficult is when you start getting more than just one or two reptiles in the house.  With just one baby, it’s easy to hit the pet store once or twice a week to pick up a dozen crickets, and then feed the bugs to your lizard right away so that you don’t need to ever keep them around the house.  When you get more animals, though, those trips can become expensive — and with growing juveniles, gravid females, or other more ravenous critters in the house, you’d need to be going every single day.  And, of course, if you live in a small town or rural area you might not have a convenient pet store to make regular trips to.  So keeping your own colonies of bugs quickly becomes a good option if you’re getting serious about your herps.

Maintaining a good diet for your reptile pets is a bit more work than just operating a can opener — but if you get yourself set up right, it doesn’t have to be difficult.  I’m going to write a few posts about some basic insect setups that are easy to get going and even easier to maintain.

One really common choice (and probably the easiest thing in the world to keep going) is mealworms:  the larval form of the darkling beetle.  They’re high in protein, and for many lizards these are a great staple food — some of the longevity records for leopard geckos have been set by leos fed on a diet of primarily mealworms.  Many types of geckos (including leos and cresties), bearded dragons, chameleons, water dragons, and many other lizards will happily chow down on these little buggies.  Mealworms also make good food for some amphibians, birds, and tarantulas.  They’re even safe for human consumption (I’m told they’re delicious if fried, but have yet to try the experiment myself).  Look up your pet’s specific needs to see whether mealworms are an appropriate food or not — as always, do your research, people!

So Just What Are Mealworms?

As mentioned above, the mealworm is the larval form of the darkling beetle.  Like most beetles, there are several stages in the darkling beetle’s life cycle.  They begin as eggs, which hatch into teeny, tiny little mealworms after about 7-10 days.  The teeny, tiny little mealworms eat and eat until they outgrow their exoskeletons, which they then shed in order to become slightly bigger mealworms.  Whenever a mealworm moults, it will be a creamy white color for a day or two before the new exoskeleton hardens up and becomes the usual brown.  Some people like to select only these white, freshly-moulted mealworms as food for their lizardy-babies, as they’re less crunchy and more easily digested at this point — but it’s definitely not necessary to be so picky.  This process of moulting happens about 10-20 times, until the mealworm is about 2cm (just under an inch) long.  At this point the mealworm will enter its “pupal” stage, a form halfway between a worm and a beetle.  When in the pupal phase, the young darkling beetle is at its most vulnerable.  Like a caterpillar in its cocoon, it won’t move or eat for several days (up to a few weeks, depending on temperature and seasonal conditions).  If prodded it may twitch, but mostly it will just lie there.  After the inner transformation is complete, one final moult will occur, and a new darkling beetle will emerge, ready to eat and mate and create a new generation of lizard food.

Pictured below are several different phases of mealworm development:

Preparing a Mealworm Colony

The most difficult part of setting up your mealworm colony is simply getting your hands on several hundred mealworms to begin with.  Smaller pet stores may not be prepared to sell you 500 or 1000 mealworms on the spot — but they’ll likely be very happy to order them in for you.  Be sure to ask about discounts on bulk purchases like this.  There are also websites where insects can be purchased, such as canadianfeeders.ca — but do be sure to do some careful research before ordering anything online.  Some suppliers feed hormones to their mealworms to prevent them from ever pupating , as a way of ensuring that customers won’t just set up their own colonies.  It’s an underhanded trick, and I myself am definitely uncomfortable with the idea of feeding hormone-doctored bugs to my lizardy babies.

Once you have your starting population, all you need is a container (or preferably two or three) that are large enough for the mealworms to live comfortably.  If they’re living all jammed together there’s a greater likelihood of cannibalism, and waste will build up more quickly.  Your container needs to have a flat bottom and straight sides so that the mealworms can’t climb out, and some ventilation so that they don’t suffocate.  I use a simple plastic drawer unit (pictured below) with two drawers measuring about 16 x 24 x 6cm.  Plastic shoebox or tupperware containers (with air holes drilled in the sides or lid) also work well, but I like the easy access of the drawers.

In addition to a place to live, your mealworms need some food to eat.  Cereal grains (like uncooked oatmeal or bran flakes) are a great option, and they also give the mealworms something to burrow in.  I put a thin layer (less than a cm) of bran flakes on the bottom of each drawer.  There also needs to be a source of water provided, but mealworms can’t drink from a water dish — they’ll drown.  Slices of fruits or vegetables will do the trick, and feeding a variety of healthy vegetable matter to your mealworms has the added benefit of making them a more nutritious meal for your lizards.  If you’re a person like me who cooks with a lot of fresh produce, you can supply most of your mealworms’ needs by simply giving them the cut-off ends of carrots and other veggies that would normally just end up in the compost.

Maintaining Your Mealworms

Like pretty much all living things, mealworms produce waste.  And when they’re living in an enclosed space, that waste builds up over time.  Keep your mealworm colony clean and healthy by removing any dried-out bits of vegetables and fruits (or if something starts to go mouldy, take it out right away).  Also try to remove any dead mealworms or beetles.  And every month or two you’ll want to do a full clean-out of the container, to get rid of as much worm poop and other debris as possible (this is where having two separate drawers comes in handy).  How I handle the big cleaning operation is to move everything into a single drawer.  I then wash and dry the empty drawer.  Then I pick out any live beetles and mealworms, and move them to the fresh drawer.  Because the eggs can’t be seen, you can’t just throw out the rest:  sift it through a fine mesh strainer.  Keep whatever goes through the strainer in the second drawer (separate from the more grown-up beetles and worms), and throw out the bits of vegetable matter and cast-off exoskeletons that get caught up in the mesh.  Toss in some new grains and fresh veggie slices for the buggies to nom on, and you’re good to go again.

Occasionally it may be necessary to buy some new mealworms to “top up” your colony, if the population gets too low.  Keep an eye on things and if you see that your lizards are consuming mealworms faster than the colony is producing them, try to increase your population.  You can also start another colony if this seems to be happening far too often for your liking:  maintaining several colonies at once means that you can harvest from one and leave the other one alone to replenish itself for a time, and then switch over when the first colony starts to get a bit depleted.

Watch for some other insects that may decide to infest your mealworm colony, such as grain moths and grain mites.  Grain moths aren’t a huge concern (except that they’re a bit of a pest to have around the house, because they’ll get into your cereal and pasta and rice if it’s not kept in air-tight containers).  Grain mites are more of a problem, as they’ll multiply rapidly and make a mess of your colony.  If you notice that you’re getting non-mealworm bugs in your colony, give things a good cleaning out and consider putting a screen top on the containers to protect the colonies from further infestation.

Feeding the Lizards

Mealworms should be dusted with mineral and vitamin supplements (according to your lizard’s specific needs) before feeding.  In most cases, a calcium supplement is the most important.  Phosphorous and vitamin D3 are also commonly important ones.  Do your research and determine what is necessary for your specific animals, because mealworms alone are not an ideal diet.

You can also mix mealworms with other feeders, such as crickets, waxworms, butterworms, roaches, silkworms, superworms, hornworms, etc.  It’s not totally necessary (as long as you are supplementing properly), but a varied diet makes it easier to be sure that your reptiles are getting exactly what they need.

Potential Hazards and Concerns

While mealworms are generally a good feeder and don’t really pose many problems, there are a couple of concerns when using them as a major feeder for your reptiles.  One is the hard exoskeletons, which may cause a risk of impaction if your lizard is eating a lot of them.  It’s extremely rare that this will happen, but impaction (which can happen for a variety of reasons) is a leading cause of death in captive lizards.  For this reason you should always be aware of how often your lizard is eating and pooping, and watch for any abnormal behaviours.  If your lizard stops eating, stops pooping, or starts behaving strangely, you may have an impacted animal.  Check for dark or swollen places on the belly, and if you’re not sure, see a qualified reptile vet.

To avoid any risk of impaction, you can try to feed mostly freshly moulted mealworms (the white squishy ones).  As I said above, though, it’s a very small risk.

Another concern with mealworms is that with lizards who don’t chew their food before swallowing (sometimes an issue with bearded dragons, for example), the mealworms may bite on the way down, causing internal injuries.  There’s some debate as to how much of a threat this really is (some highly respected reptile specialists scoff at the idea), but if you are noticing that your reptile tends to swallow its mealworms whole and this is a concern to you, you can either a) switch to feeding larger prey items that will require chewing, or b) kill the mealworms before feeding them to your pet.  Be aware that some animals won’t take to eating pre-killed foods, so the first option is sometimes the only one.  Larger prey items may include crickets, silkworms, superworms, hornworms or roaches.