It is organized into the following subsections:
- What They Won’t Eat
- Commercial Diets
- How Much and How Often
- How to Do It
- Problem Feeders
“What should I feed it?”
That’s easily the most common question asked by beginning garter snake keepers. It’s also the most important, because garter snake diets are tricky, and feeding your snake the wrong kind of food can have serious — even fatal — consequences.
It’s also a question that frequently gets a lot of wrong answers, from pet store workers who insist that they eat crickets, to hobbyists who get confused about which fish have a potentially dangerous enzyme, and which don’t. That confusion can frighten a beginning garter snake keeper into believing that even one mistake can have dire results.
Fortunately, even the most serious problems can be avoided with a little knowledge. A garter snake’s diet does not have to be a cause for concern, as long as you know the pros and cons of each food item. That’s what you’ll learn on this page.
What to Feed
Unless you have a garter snake that eats mice, you must feed your garter snake a varied diet to ensure complete nutrition. Mice represent complete nutrition, but other foods are deficient in some way and must be fed in combination or supplemented to ensure a complete diet.
A young garter snake that is not eating pinky mice or pinky parts may be fed a combination of earthworms (cut into appropriately sized pieces if the snake is small and the worm is big), feeder guppies or platies and, if the snake will accept it, pieces of fish fillet. Supplement the fish and worms occasionally as set out below.
While this is a healthy diet for a garter snake, it does put the snake at risk of a parasitic infection that may be very hard to treat. Ideally, the snake should be converted to a mouse-based diet as soon as possible. Begin with pinky parts if the snake is too small for pinky mice; scent the mice to encourage the snake to feed if necessary. Once converted to mice, a garter snake should eat them most of the time; fish and worms can be offered occasionally if you like.
Frogs and Toads
In the wild, most adult garter snakes feed preferentially on frogs and toads. In a perfect world this would make up the bulk of their diets. But in captivity, frogs and toads should almost never be used.
Frogs, toads and tadpoles are rife with parasites, and are quite likely to transmit them to your snake. It’s true that wild garter snakes eat frogs and toads all the time, but they’re (a) used to it and (b) rife with parasites themselves. Your pet garter snake won’t necessarily have the same resistance as a wild garter snake whose immune system has been hardened by constant exposure. As a result, frogs and toads shouldn’t be used as garter snake food unless the snake refuses to eat anything else.
There may also be legal restrictions on collecting amphibians where you live.
There are some concerns about parasite transmission with earthworms as well, and worms collected from roads, sidewalks and golf courses during rainstorms, while convenient, may contain toxins.
On the other hand, some species of snake will want these more than anything else, and most baby snakes will prefer earthworms as well. For many garter snakes, worms are often the one food they will reliably eat. So far, I haven’t encountered any problems that I’ve been able to attribute to earthworms.
Worms collected from your garden (“dew worms”) will be eaten with particular enthusiasm, and nightcrawlers (Lumbricus terrestris) purchased at a bait store will also suffice. Be careful with nightcrawlers, which are big and muscular: be sure to cut them into small pieces when feeding them to small snakes; they’re strong enough to crawl back out if you’re not careful! Cutting a large nightcrawler into quarters will be enough. Cut them into too-small pieces and the snake may ignore them: they expect their worm prey to twitch a little.
Never use red wigglers (Eisenia foetida), which are the worms used in vermicomposting and are sometimes sold as trout bait: they are reportedly toxic to garter snakes. There is apparently another species of red worm used in vermicomposting that is fine to feed to garter snakes, but unless you’re certain which is which, it’s best to avoid vermicomposting worms, to be safe.
Worms are also deficient in calcium, though there is some debate about whether this is a cause for concern; as a precaution, if your garter’s diet is mostly worm-based, supplement it periodically with calcium. See Supplementation, below, for details.
Some garter snake species won’t normally eat earthworms, such as ribbon snakes and some western aquatic species. And sometimes finicky individuals of species that normally do eat earthworms will turn up their noses at them: I once had a melanistic Eastern Garter Snake and an Eastern Black-necked Garter Snake that never ate them.
Many keepers rely on fish because it’s very easy to find, and because it’s easier to control parasites with freezing. But there are some problems with using fish as a food source that lead me to recommend that you not use it unless you absolutely have to.
Live fish can be advantageous because some garter snakes will refuse to eat anything else. They can also be a great way to get a baby or smaller garter snake feeding, particularly if they need to see their food move (and they’re not comfortable with you wiggling food at them; see Problem Feeders, below).
But a regular diet of live feeder fish can expose your snake to several medical problems. Live fish can carry a load of internal parasites with them that can leave your snake with a persistent infection of roundworms, tapeworms or pinworms that can be difficult to treat. Symptoms of that infection can show up months after the snake ate the contaminated fish. (See Internal Parasites.)
Certain kinds of live fish can pose additional risks. Goldfish should be avoided at all costs; it’s essentially a junk fish with poor nutritive value. And other species of fish contain an enzyme called thiaminase, which destroys vitamin B1 (thiamin) and gives your snake a potentially fatal vitamin deficiency (see Vitamin B1 Deficiency).
As a result, I do not recommend using live fish unless the snake will not eat anything else, and I recommend against purchasing garter snakes that will only eat live fish if you can.
Pro: Some garters will ignore other food but eat live fish. Most garters will eat fish. Fish fillet is relatively inexpensive.
Con: Live fish frequently carry parasites. Some fish carry an enzyme that leads to a serious vitamin deficiency. Goldfish are not good for garter snakes. Live fish are expensive in quantities sufficient to feed a garter snake. Not every garter snake will accept fish fillet. Fish fillet is nutritionally deficient without supplementation. Results in watery, smelly feces.
Frozen whole fish do not present the same problems with parasites (if frozen for more than 30 days), but freezing does not destroy thiaminase. Fish fillet is very convenient, because it can be bought frozen at the supermarket, but it’s not complete nutrition. A garter that lives on strips of fish fillet misses out on the nutrients found in whole fish, so periodic calcium and vitamin supplementation will be necessary. Fish fillet can be safe to use (ocean perch, for example, is known not to contain thiaminase) but it should not be the only item in the snake’s diet. It’s fine in combination with worms or mice.
Alan Francis, a British garter snake keeper, has come up with a recipe for homemade garter snake food based on trout purchased from a nearby trout farm: whole trout are put in the blender, mixed with gelatin, set in blocks and put into the freezer. Strips are broken off as needed. I haven’t tried it yet, but it certainly sounds like a good idea: trout are a safe fish as far as thiaminase is concerned, and freezing takes care of the parasites. The recipe is available on his website.
Although not considered a “natural” diet in the wild, garters will eat rodents in the wild from time to time. In captivity, garters have been fed mice with no apparent ill effects for years. I’ve certainly done so: several of my garter snakes have been eating mice for a decade or more.
The main advantage of using mice is that they are more nutritious than fish or worms: they do not require supplementation and there is no risk of a thiamin deficiency. Garter snakes feeding on mice don’t need to be fed as often and they grow faster, too. Another significant advantage is that garter snake feces is a lot less watery and smelly!
There are, in fact, only two disadvantages to using mice, and neither of them have anything to do with their nutritive value. Some keepers may not be comfortable feeding mice to their snakes — in fact, they may have chosen garter snakes so that they wouldn’t have to feed mice to them.
And not every garter snake can be trained to eat them; while most of my garter snakes have taken to mice without difficulty, I’ve had several stubborn individuals who wouldn’t touch them, or were simply too jumpy to be offered them.
The key thing to remember is never to use live mice. (This alone may make some keepers feel more comfortable with the idea.) Using frozen mice is safer for the snake and more humane for the mouse. You can buy them at many pet stores or directly, in bulk, from rodent breeders.
Mice come in different sizes: pinkies are newborn mice, followed by fuzzies, hoppers, jumpers and adult mice. A baby garter snake is too small to eat a pinky mouse, but can eat pinky parts or a small pinky after a few months. Adult males and young females may eat hoppers and large adult females may eat adult mice. See How Much and How Often, below, for more details.
Thaw the mouse out before offering it to your snake. This can be done at room temperature, or in a plastic bag in warm water. More direct methods are problematic: mice heated under a lamp may burst, and mice defrosted in a microwave will explode!
Training garters to eat mice is usually not difficult. Rub a pinky or fuzzy mouse with fish or earthworm to transfer the scent to the mouse. This can be quite effective, especially if the garter is already used to eating non-moving food like fish fillet.
Some garters need no scenting at all and will take mice immediately, and some baby garters will take unscented pinky parts (chopped up pinky mice, cut up when frozen) before they’re big enough to take a whole pinky! Others may stubbornly refuse them, especially if they expect their food to be moving.
Rat pups are another possibility, especially for large female garter snakes. While adult rats are obviously too large to be fed to garter snakes, pinky, fuzzy and even hopper rats can be used. Pinky rats may be useful in cases where the snake doesn’t like eating furry food: i.e., it’s big enough to eat fuzzies or hoppers, but prefers to eat pinkies.
Garter snakes have been known to eat slugs and leeches in the wild. Slugs are high in calcium and are recommended; they’re just not as easy to get.
As for newts and salamanders, they run the same risk of parasites as frogs and toads. Some newts are also quite toxic; while some garter snake populations have evolved resistance to newt toxin, others (even from the same species) haven’t. Avoid them to be on the safe side.
A few species will eat small lizards and snakes, which should be avoided for their parasites alone, to say nothing of the discomfort many of us have with the idea of feeding reptiles to reptiles.
As with frogs and toads, collecting newts, salamanders, lizards or snakes from the wild may have legal implications.
What They Won’t Eat
Certain species will prefer some food items and avoid others. Garter snakes are a tremendously diverse group of species: some are generalists that will eat almost anything; others have a more specialized diet.
For example, ribbon snakes and some of the western aquatic species will not normally eat earthworms or slugs. Some species are better at catching live fish than others. And some are a lot harder to train to eat mice than others.
Sometimes this is because of their species. Sometimes this is because a given snake is from a range where its species has specialized on certain prey items: I’ve heard that melanistic Eastern Garter Snakes descended from Long Point, Ontario stock strongly prefer fish to earthworms, even though other Eastern Garter Snakes are much less picky; that was certainly the case for the one I kept. And sometimes it’s because the individual snake is being picky and stubborn; see the section on Problem Feeders below.
In general, though, garter snakes are extremely unlikely eat to crickets, mealworms or other insect larvae, no matter what the nice person at the pet store told you — they are simply not insectivores.
And all snakes are carnivores; they will not deliberately eat any vegetable matter of any kind. In fact, they are physically incapable of digesting it!
Earthworms are deficient in calcium, and fish fillet is not nutritionally complete. If either of these items is a frequent part of your snake’s diet, you may want to consider adding vitamin and mineral supplements from time to time — once or twice per month at most.
I have used a combination of powdered calcium, vitamin B1 (as insurance against vitamin B1 deficiency) and vitamin D3 (to help metabolize the calcium). Health food stores will have these in tablet form, which you can crush; pet stores will carry powdered calcium supplements.
I’ve received a report that using calcium powder on earthworms will kill them. Lightly dust them instead of dredging them in the powder, and do it just before feeding. Either that, or use liquid calcium supplements, available at pet stores.
When supplementing, don’t overdo it. While vitamin B1 is water-soluble and, as such, theoretically impossible to overdose on, it is possible to get too much calcium and vitamin D3. Most calcium powders include vitamin D3; check the label.
A couple of commercial snake diets are on the market, one in the form of sausages and one that is specifically marketed as garter snake food. While there may not be anything conspicuously wrong with them, they are not cheap and offer no special advantages over natural food. They may be helpful for people who are squeamish with worms or mice, and for those who have trouble acquiring other food sources. But I wouldn’t use them.
How Much and How Often
How often you feed your snake depends on what you feed it, and how much depends on the size of the snake. Worm eaters need to be fed more often than fish eaters, which in turn need to be fed more often than mouse eaters. Worm eaters should be fed twice weekly, fish eaters can be fed every five to six days or so, and mouse eaters every week. Very young garter snakes can eat a bit more frequently than that: they could probably eat every second day on an earthworm diet.
A rigid schedule is not strictly necessary, though it’s easier for the keeper to remember. Snakes that eat a varied diet can be kept on a constant schedule, despite the different recommended intervals I just mentioned. Don’t agonize too much about the schedule unless you have very young snakes; it’s very hard to starve a snake.
You should feed your snake enough to leave a visible bulge, but not so much that the snake is going to burst. A baby snake should get two or three small earthworms collected from the garden, or one-quarter to one-third of a large bait store nightcrawler, or a few feeder guppies, or one large feeder platy, or one-quarter to one-half of a pinky mouse. Smaller, more frequent meals are more easily digested than mammoth, infrequent meals. In general, baby snakes should be fed frequently.
It’s hard to make fatal mistakes, and through trial and error you will figure out how much and how often based on how big the snake looks after a meal, and how fast that meal is digested. Sometimes the snake itself will tell you: if an ordinarily tame snake nips at your fingers when you reach into its cage, it’s likely that it’s just very hungry.
It is possible to overfeed your snake. Since overfeeding causes obesity and reduces the snake’s lifespan, it should be avoided. Do not feed your snake every day or it will become obese. It’s harder to overfeed on a pure earthworm diet, but easier on a pure mouse diet, because mice are more nutritious than worms. Again, it’s quite difficult to overfeed a baby garter snake.
Note that a snake’s metabolism goes up and down with the temperature: a snake kept in a house without air conditioning during a warm summer will get hungrier faster than a snake kept at cooler temperatures.
How to Do It
Okay, I’ve shown you what to feed them, how much to feed them and how often to do it — now how do you go about feeding them?
Most of the time it’s fairly straightforward. Our garter snakes’ cages have paper towels for substrate (rather than wood chips or bark), and they all eat frozen/thawed mice, so all we do is drop the mouse into the cage. It usually doesn’t take the snake very long to find it and eat it, but it depends on the snake: our Wandering Garter Snake is pretty instantaneous; our Checkered Garter Snakes need more time.
If you’re using a different kind of cage bedding, you’ll want to ensure that it doesn’t get stuck to the food. I wouldn’t drop earthworms into a cage full of wood chips, for example, because I’d worry that the wood chips would get stuck to the worm and be swallowed by the snake. Snakes don’t digest plant fibres well at all.
If I were feeding worms, dead whole fish or fish fillet, I’d use a small plate or dish.
Whether whole or in fillet, frozen fish should be thawed and not cooked.
Live fish would be offered in a small, water-filled bowl from which the snakes could catch fish at their leisure.
Some garter snakes need their prey to move. Garter snakes are very visual, more so than many other snakes, and respond well to motion. This is not a problem with live fish or live worms, but worm pieces (if the snake is very small), fish fillet or frozen/thawed mice may hold no interest for them. In that case you may have to offer the food on tongs, hemostats or tweezers, wiggling it around to simulate motion and stimulate the snake. This is called tease-feeding. (You don’t want to hold the food in your fingers. That’s a good way to get bitten: snakes sometimes miss.)
If you keep two or more snakes in the same cage, you may have to feed them separately in order to prevent food fights and other accidents. See the section on keeping more than one snake in the same cage to learn how to deal with it.
In my experience, garter snakes can be some of the most reliable and aggressive feeders of all captive snakes. But there are always a few exceptions. Here are some possible reasons why your garter snake may not want to eat.
The first and most likely possibility is that you’re offering the snake something it doesn’t want to eat or doesn’t recognize as food. Some garter snakes expect their prey to move; as a result, fish pieces, thawed pinkies, and earthworm pieces cut too small for them to twitch may be ignored. You may have to experiment: try larger pieces of worms (big enough to still be twitching) or smaller, whole worms; wiggle the food in front of the snake with a pair of tweezers; offer something else. Use live fish only as a last resort, but sometimes a garter snake needs a few live meals before it can be weaned onto something better.
You might also be offering it the wrong food. Remember that some species don’t eat certain things — ribbon snakes don’t eat worms, for example. Check the dietary preferences of your snake’s species.
Sometimes garter snakes lose their appetite when winter comes. It may be a sign that you should hibernate (or, to be more technically correct, brumate) your snake. Artificially brumating a snake is a lot less difficult than you might think; see Hibernation.
But sometimes I’ve found that garter snakes don’t go off their feed altogether, they just get finickier. For example, I’ve had a few snakes that had been converted to mice suddenly refuse to eat them when October rolled around, but they did eat when they were offered worms or fish. After a while they began taking mice again. So try feeding your snake something else. Earthworms are frequently a reliable fall-back choice.
Another possibility is that you have a male garter snake and it’s mating season. When he was introduced to his mate, my male Red-sided Garter Snake refused to eat for two months; I might have gotten a few worms into him during that time, at best. He was completely preoccupied with mating.
Finally, the snake might be too nervous to eat — especially with you watching it. There are some things you might want to try. If the snake has just arrived, give it at least three days before offering it any food — give it time to adjust to its new cage. Leave the snake alone while feeding: it might be too terrified of you to pay attention to the fact that there’s a tasty morsel in front of its nose. And if it’s being housed with another snake, consider separating them: it’s possible that the other snake’s presence is stressful.
The worst-case scenario is when a snake needs its food to move but cannot eat in front of you — in other words, you can’t tease-feed it. In that case you have little choice but to feed it live food (fish and earthworms) and hope that it settles down enough at some point that you can switch it to something healthier and safer.