Mealworms are a great live food for reptiles, and they make a perfect addition to your pet’s diet. They’re healthy, nutritious, and most importantly, they’re affordable. Here’s everything you need to know about keeping mealworms as a reptile feeder.
Healthy Mealworms = Healthy Reptile
Before you start feeding mealworms to your pet reptile, it is important to ensure that they are on a healthy diet themselves. Mealworms are easily able to absorb the nutrients in the food they eat, and if they are not properly nourished, these deficiencies can be passed on to your reptile. A healthy diet for mealworms includes plenty of fresh fruits and vegetables, as well as a good quality protein source. You can either purchase a commercially prepared mealworm diet or make your own.
Keeping or even breeding healthy mealworms, full of essential nutrients and micro-nutrients, is actually quite easy. Keep reading to get a simple step-by-step guide to raising high-quality feeder insects.
Lifecycle of a Mealworm
A mealworm’s life cycle starts when the female lays her eggs. Depending on the species, a female can lay anywhere from 30 to 500 eggs at a time. The eggs hatch into larvae, which look like small grubs. These grubs are what we usually call mealworms.
The larvae then go through a series of molts, gradually growing larger with each shedding of their skin. About 5-10 days pass between each molt. Each cycle of molting and then growing is called an instar. Mealworms usually undergo around 10 to 20 such cycles.
After molting, mealworms are the lightest in color – a soft tan, yellowish color. This is the perfect time to feed them to your reptile, as their shell is very soft and won’t cause digestive issues.
Right before molting, mealworms are quite dark in color – from dark browns to almost black. At this point, their chitinous shell is very hard, and is likely to cause problems such as impaction with your reptile.
Eventually, the larvae turn into pupae. At this stage, they stop eating and enter a state of dormancy. After about two weeks, the pupae emerge as beetles – as Tenebrio molitor, a species of Darkling Beetles, specifically.
As a beetle, the mealworm mates and lays eggs, starting the cycle anew. Mealworms go through this entire cycle in around three months. However, they can remain in the larval stage for up to two years if conditions are not ideal for molting or pupating. Different species of mealworms have different lifespans as adults, but most only live for a few months.
Substrate (feed) for Mealworms
The substrate is the base food source as well as the ground that the mealworms will live on and burrow in. It needs to be dry enough to prevent mold and bacterial outbreaks, as well as a healthy food source – and ideally, it is cheap, too. Let’s go through it in details.
There are a few important factors to keep in mind when choosing a substrate for your mealworms:
First, you’ll want to make sure that the food is high in protein and low in fat, as most reptiles need more protein than fat.
Second, you’ll want to choose a food that is easy for the mealworms to digest, as they have a very simple digestive system.
Third, you’ll want to make sure that the food is not too high in moisture, as this can lead to mold growth.
And fourth, you’ll want to make sure that the food is not too high in fiber, as this can slow down the mealworms’ growth.
Some good options for mealworm feed include:
- bran flakes
- oatmeal or rolled oats
- cornmeal
- wheat flour, wheat germ, or Wheaties
- ground-up dry dog food
Cheap Substrate options
Oats, corn, and wheat are very popular options as they are cheap, easy to get, and still healthy. Keep in mind that anything you use needs to be ground to a sand-like substrate.
You can also use left-over natural cereal – but don’t use kid’s cereal with high sugar or chocolate, or artificial additives. The more natural the better.
You can usually get ground oats or corn for less than a dollar per pound, which makes it ideal for a cheap substrate for your mealworms.
Sterilizing Food – Why you should, and how to do it
One important step that many people forget is sterilizing the substrate. When buying a substrate like grains, you might get some grain mites in there. These are tiny, but they bite and can harm your mealworms. To prevent a mite outbreak or any bacterial infections, you need to sterilize any grains before putting it into the container.
To sterilize the substrate, place it on a baking tray, then put it in the oven at around 130-150°F (55-65°C) for about twenty minutes. This should kill any grain mites that could hide in it, as well as prevent other common problems.
Repeat this with any substrate you want to add to the container before doing so!
Diet for Mealworms
In the wild, mealworms are scavengers that eat a variety of dead and decaying organic matter. This makes feeding them quite easy. A healthy diet for a mealworm includes fresh vegetables, fruits, and grains. Many pet stores sell commercial mealworm food pellets that can be used as well.
When feeding mealworms to your pet, it is important to provide a variety of different foods to ensure that they are getting all the nutrients they need. Essentially, everything you feed your mealworms, you indirectly feed your reptile. A healthy diet with plenty of vegetables and greens provide your mealworms, and thus your reptile, with the necessary vitamins.
That’s why the substrate is only half the diet – it has the basic nutrients, but tends to lack the micro-nutrients like vitamins and minerals.
Food choices for Mealworms
If you have fresh vegetables and greens in your daily diet, many of these are great to use as mealworm food, too. And if not, no judgement – even though you need some veggies just as much as the mealworms!
Popular options include:
- Apples
- Carrots / baby carrots
- Squash
- Potatoes
- Leafy greens (except lettuce)
- Turnip greens or similar greens
Most other veggies and greens you’ll have at home will be fine, too. What’s important is that they have some moisture, but not too much – otherwise, they may rot quickly. You should also not feed grilled or otherwise prepared vegetables – fresh and raw is best.
However, there are a few foods you should avoid for health reasons:
- Citrus fruits (too high in citric acids)
- Pineapple
- Kiwi
- Avocado
- Rhubarb
- Broccoli & Kale (can interfere with Calcium absorption)
These may be okay for the mealworms, but are toxic to many geckos! Again, what you feed your mealworms, you indirectly feed your reptile.
To feed your mealworms, simply cut the vegetables into smaller bits and throw them into the mealworm container. If you notice any mold or rotting, remove the food immediately – otherwise, you can leave it in until it’s fully eaten.
Because of the potential of rotting, it’s best to not provide too much food at once – feed about as much as they can eat in a week. Depending on the number of mealworms you have, a few small pieces should be enough.
Cheap Mealworm sample diet
A cheap and simple diet for mealworms could be store-bough oatmeal or rolled oats – about 2-3 inch deep in the container. Then, add a few pieces of apples, carrots, or squash to it. Once these are gone, add some new veggies to the box.
You can also add mealworm feeding mixes – but make sure that the one you buy is okay for your reptile! Different reptiles have different needs, and the wrong feeder mix can cause issues with your pet once they eat the mealworms.
Gut-Loading Mealworms
If you’re feeding mealworms to reptiles, it’s important to “gut load” them first. This means giving the mealworms a nutritious diet for a day or two before they’re fed to your reptile. That way, your reptile will get a good dose of nutrients when they eat the mealworms – as the gut-loaded food is still in the worm’s gut.
There are a few different ways to gut load mealworms. You can purchase a commercial gut loading product from a pet store, or make your own by blending up some dark leafy greens and other vegetables.
If you are already providing healthy vegetables as part of their regular diet, you don’t have to do much here. It’s a good idea to still give them special feeder mixes to eat in the 24 hours before feeding them to your reptile. Especially calcium is important for most.
I have another, more detailed article on gut-loading mealworms if you want to learn more.
Moisture for Mealworms
Mealworms needs some water, or moisture, to survive and grow. However, they don’t drink water. Instead, they get their moisture from foods with good moisture content – like apples, carrots, or many greens.
As long as you already feed vegetables like that, you don’t have to do anything.
Also, do not provide a dish with water! Mealworms can’t drink from it like that and will drown.
Container for Mealworms
When it comes to keeping mealworms, there are a few different options. Some people like to use a plastic container with a lid, while others prefer a glass jar. Personally, I think that a plastic container is the best option. It’s lightweight and easy to clean, and the lid helps to keep the mealworms from escaping. Plus, if you choose a clear container, it’s easy to see how many mealworms you have at any given time.
However, whatever type of container you use, make sure that it has ventilation holes. Mealworms need oxygen to survive, so a closed container will quickly become cramped and humid. By giving them some airflow, you’ll help to keep them healthy and active.
Tip: Make sure the container is relatively high. You’ll want to add about 2-3 inches of substrate, then the worms, and then still have 2-3 inches of smooth, plastic wall – this prevents the mealworms from escaping.
Temperature, Lighting, Humidity
A good temperature for mealworms is about 77-81°F (25-27°C). However, this is for healthy growth and breeding. To keep your mealworms in their larval state as long as possible, keep them in a colder environment – like a fridge. Temperature below 62°F (17°C) slows their growth and makes pupating much less likely.
For feeding them to your reptile, keeping them just below 60°F (16°C) is generally the best option. Keep in mind that not only their growth will slow down, but also their eating. They will need less food in the fridge. However, the food will also rot much slower in the fridge, which is another plus.
Take the mealworms out of the fridge before feeding them, though. Pick the number of mealworms you’ll feed and put them in a separate container for 24-48 hours. There, you can offer them fresh veggies and a gut-loading mix. This is also to get them back to room temperature. Most geckos don’t enjoy dead food, and cold mealworms move minimally, similar to almost-dead insects.
Mealworms have essentially no lighting requirements.
Humidity should be “normal” – too high and you’ll encourage rot in the container, but if humidity is very dry, they might suffer, too. In most circumstances, normal humidity, as you have it in your room, is just fine. Just make sure there is enough ventilation in the container to prevent a buildup of humidity.
Mealworm Care & Breeding
Mealworms are quite easy to care for. They don’t need much beyond a container filled with substrate, a few vegetables, and a few air holes for circulation. They do prefer warm temperatures, but to keep them from pupating, cool temperatures are better.
The only thing they’ll need is for you to check in every few days to make sure that no food is rotting. If kept unchecked, rot or mold can quickly ruin the entire container. A small spot is no big issue, but if you see mold that has spread, it’s the safest choice to throw the entire container full of mealworms away. Unhealthy feeder insects makes an unhealthy pet!
If you want to breed your own mealworm to save cost, all you really need is a few small containers. At the very least, you need to keep the beetles and the larvae (mealworms) separate. Keeping the pupae in a separate container is also good, since the beetles or worms may eat them!
Read up on breeding your own mealworms here, it’s actually quite easy and can save you one expense for your pet.