Mealworm Care

Maintaining a mealworm colony is simple – try it as a pet, for a school project or just for fun!

Food & water

Mealworms have very simple tastes in food. The best part is, their food doubles as their bedding. Simply line the mealworms’ home with any dry grain or cereal, like rolled oats or bran. Make sure the surface of the bedding is at least 4 cm from the lip of the container. Like any living thing, mealworms need something to drink. A little dish of water won’t do it, though – mealworms need to get their water from something solid, like a vegetable. Put slices of carrot, celery, potato or green pepper (or any other fruit or vegetable) on top of their bedding. Choose a vegetable that won’t go mouldy too quickly, and exchange the pieces for fresh slices every 5-7 days. Vegetable scraps work well – try using the ends of celery or carrots that would have been composted otherwise.

Shelter

House your mealworms in a container at least 8 cm deep and made of a smooth material; glass, plastic or metal work well. Mealworms can climb cardboard and fabric and so will escape from containers made from anything they can grip. The beetles can’t fly, so the containers don’t need lids. If you decide to use a lid to avoid spilling, be sure to provide air holes!

Caring for life stages

Mealworms start out life as an egg, then hatch into a larva, morph into a pupa, and finally emerge as a beetle. (Read all about their life cycle in the ‘Mealworm Life‘ section). Both the beetles and larvae will eat the immobile pupae, so it’s important to keep the life stages separate. When you spot any pupae lying on top of the bedding, take them out and store them in a container lined with paper towel. They don’t need food because they don’t eat during this stage. Cover them with more paper towel in case they emerge upside down and need something to grip. You can store the beetles either in their own container or in the same container as the larvae. It’s ideal to store each life stage separately, but it’s a lot more work.

Cleaning

Every so often you will need to remove the mealworms’ waste. Their poop looks sandy and will collect at the bottom of their container. It’s easy to remove by pouring everything into a sieve; the poop will fall through. Because mealworm eggs are quite small, most of them will also fall through. If you’re interesting in maintaining a colony, keep the sifted poop in ‘quarantine’ with some added food and vegetable until the larvae are big enough to scoop out.

Harvesting

If you decide to harvest larvae for food (either for you or for a pet), wait until they’re nice and big. Separate them from their bedding either by sifting them through a sieve or by picking them out one by one. Mealworms like climbing screen-type material, so even if all of their bedding doesn’t fall through the seive, wait a few minutes for them to start climbing, and then lift them out with a spoon.

Pests

Although some people would consider mealworms themselves to be pests, there are a few other creatures that can interfere with your thriving colony.

Grain/meal moths

These are small, grey, triangular-shaped moths. Their larvae look like little white inchworms and spin a web in the bedding. You’ll know if you have this infestation because you’ll see moths fluttering around, and you’ll find webs in the bedding. These moths don’t eat fabric, but they can infest your own food, so make sure your kitchen grains and cereals are sealed tightly. To get rid of them, set out meal moth traps (pheremone-based glue traps available in most hardware stores) and kill any adult moths you find. The moth larvae are very difficult to find in the mealworm bedding, but if you find any, remove them right away. Be sure to kill them, because unlike mealworms, they have sticky feet and can climb out of anything.

Mould

Mould is often caused by too much humidity in your container. If you find mould growing, try using a drier vegetable as your water source. Leave the top slightly ajar to let air flow through. Finally, get rid of any obvious mould you see and replace it with fresh bedding.

23 thoughts on “Mealworm Care

  1. An easy way to harvest mealworms is to very finely mist 2-3 sheets of paper towel with water, only enough that is hardly damp. Fold over a couple of time and lay it on top of the bedding. I do this at night and in the morning the towel is full of mealworms. 2-ply sheets will separate and the worms will crawl between the layers.
    I use them to feed the birds and 2-3 sheets give me about 50-80 mealworms.

  2. Hi everyone. I have a question. Whenever I check the meal worms box, i see that the pupae are eaten with meal worms. In fact the other meal worms eat the pupae exactly after they begin their cycle ( from adult meal worm to pupae) and I have really no time and chance to separate them!
    What can I do now?

    1. Hi Mehrdad, just make à backwards calculation on what amount of mealworms you would like to produce. Than separate that amount of larva(same age) and put them in à separate little container. Since they are all about to pop they wont eat eachother( they have eaten enough). So lets say you want to eat 40 grams à week in à couple of months. Thats 200 mealworms à week and about 10 beetles to lay that amount of eggs à week. That means you just need to separate 10 pupas/larva à week to maintain the eggflow. I’ve learned this by experience so this works for me. I hope you find it helpful. Greatings thomas

  3. I have three mealworms in the pupa stage in the container i got the mealworms in for my beardie. However, the one is still half connected to his exoskeleton. Hes been like that for almost 4 days now. Is he stuck? Should i help him free from it? Two days ago, i noticed they’d wiggle when i slightly touch them, now their not wiggling at all. Could they have died? I keep them at room temperatures and keep them covered in a circular tupperware. Any ideas? Any comments would be MUCH appreciated. This is my first time caring for mealworms and i wanted to raise them until they turned into darkling beetles. thank you guys!! :)

    1. I’ve seen that before – sometimes they do get stuck. I don’t suggest trying to help them, because it’s likely that by interfering you might make it worse. If it stopped moving, it’s possible it might be dead. That’s just a fact of life with the mealworm colony – sometimes the little guys don’t make it :(. Try to make sure the pupae are separated from both the larvae and the adult beetles. Since the pupae can’t defend themselves, they often get nibbled if they’re left with the larvae and beetles.

  4. Love your website! I used to breed masses of mealworms for reptile food and am now considering their other uses.
    My personal favorite way to collect them was to lay a damp rag on the surface of the bedding for 10-20 minutes then gently left it and brush them into another container. (They will be clinging to the underside.) This can be repeated a few times and works best when they haven’t had fresh carrots that day.

  5. Thanks for your informative website! I am 6 weeks into mealworm farming in Hawaii and have been diligently separating pupae from beetles thanks to the forum’s suggestions. Just one more question..Do mealworm larvae eat beetle eggs? I am trying to minimize containers and want to maximize production. I have a large sweater box with the larvae and a rectangular colander within this box containing the beetles (the pupae are raised above the beetles on a disposable plastic container). In theory, the frass from the beetles falls through the colander and lands into the larva container with the eggs. I just wanted to make sure the eggs are safe with in with the wheat germ/larvae box.

    1. I think the eggs should be safe in the larva box. I had the same setup – the eggs would sift down into a lower box to be separated from the beetles. After they hatched and grew into larvae, I didn’t remove the larvae from the box. One thing you can try is to rotate the box that collects the beetle detritus every few weeks. Then, each larva box will just have a few weeks’ worth of eggs, so that by the time the larvae grow bigger, there aren’t any eggs left. It also makes it easier to harvest them because you can safely throw away the frass knowing there are no eggs left.
      Good luck!

  6. I’ve noticed I have some very small pupa which turn into very small beetles.
    1. Why are they so small? Not enough food?
    2. Should they be removed for genetic reasons? I’m thinking as fast as the multiply, if you get a few with bad genes, itll spread quick…thanks!!!

    1. How small are they? Do you have some small beetles and some big ones? What kind of larvae did you start with – regular or jumbo?

      1. They’re almost 1/3 of the size of the bigger beetles. There are a lot of big beetles as well, but every once in awhile I get some small ones or some that look like they can’t quite morph all the way into a beetle. I think I just bought large mealworms…I made sure they weren’t super or giant.

        I’ve been getting rid of the half morphed ones (chicken food)…but I’m wondering if it’s something I am doing or just bad genes? It’s only the second generation so inbreeding shouldn’t be the reason.

  7. I’m going to experiment with it and make separate beetle bins: one for the small beetles and one for the large beetles. I’ll let you know in a few months if there is a difference in meal worm size…

    1. Hi Dee, If your mealworm larvae are overcrowded in their container or if the humidity is too low (or they are not getting enough moisture) then your larvae will pupate prematurely. This means that the worms will be smaller when they turn into pupa…so the pupae will be smaller, which means that you will end up with smaller beetles. Don’t worry about this though, it is environmental not genetic. And besides, just because the beetles are smaller doesn’t mean they aren’t breeding as well or producing just as many eggs as the larger ones. Another experiment you can try to help prove this point is isolate one single mealworm into a container by itself at a young age. Be sure to give it enough food and moisture. Watch what happens. Your mealworm will grow very large, produce a very large pupa, and subsequently a very large beetle. Why is this? The mealworm will delay turning into a pupa if it senses (presumably through pheromones) that no other mealworms are around. It will continue growing bigger and bigger “waiting” to pupate until it encounters other mealworms, i.e. potential future mates. Eventually it will have to pupate and continue its life cycle even if other mealworms are not around. The beetle that emerges from this pupa will also be very large.

  8. This is my first time. Doing well. Started with 1000 meal worms, have beetles and Pupae. But it looks like alot of the Pupae have dried and there hard. They dont wiggle anymore. Been pupae a week now. Is this normal? I should just wait?

    1. They usually stay in the pupa stage for up to 3 weeks, so I wouldn’t worry about the time. If they are drying out and not wiggling, they may have died. That happens and I wouldn’t worry about it unless ALL of your pupae are dying. Wait a couple of weeks and see what happens. If they turn dark brown or black, they’re definitely dead. :(

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