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How To Raise Mealworms


How to raise mealworms (Tenebrio molitor)
Everyone who has a small flock of chickens should raise mealworms, not because they need them, but because they love them.   It's very easy to do and once set up they are virtually maintenance-free and very inexpensive.  I give my girls a hand-full or so a day; they think fresh mealworms are the best treat in the world.
1. You need a container; I prefer 10 gallon aquaria.  They allow you to see the condition of the substrate and the glass keeps them from climbing out.  You can also use a plastic tub.  Keep in mind that it is better to have greater surface area than depth.  Never cover it with anything that restricts airflow, especially if you live in a humid environment; but a wire cover is good to keep the lizards, geckos and mice from eating everything if you keep it outside.
2.  Add about 3" of wheat bran to the bottom of the container.  I get mine at grocery stores that sell food in bulk bins, but you can also get it at feed stores.  You should get it for $1/lb or less (buy about 4-5 lbs to start).  You can also use chicken feed, provided it does not have diatomaceous earth (DE) added.  I would highly recommend freezing any grain product for a couple of weeks or heating it to 130 degrees for 15 minutes prior to adding it to your colony to limit unwanted pests.
3.  Add some mealworms, the more the better and the faster the start-up will be.  I recommend starting with at least 1000 for a container the size of a 10 gal. aquarium.
4.  Add some vegetable matter.  I use potatoes, carrots, apple peals, celery stumps, watermelon rinds, whatever kinds of scraps are available.   Feed them as often as you'd like.  The more you feed them, the more they multiply.  Strive to provide consistent access to vegetables for the best productivity.   You don't want it to ever get wet inside, the wheat bran must remain dry.  Most colony failures are a consequence of excess moisture, which can spark outbreaks of fungus and mites.  I live in one of the driest places in the world and I never add moisture beyond that contained within vegetable matter--and I also avoid adding high water content vegetables.  The more varied the diet, the better the worms are as food.  Be observant when adding new foods and immediately remove anything that they won't eat to avoid rot. 
5.  Keep your colony in the shade, outside heat (even in Arizona) is great for them but direct sun or rain will kill them.  The warmer they are kept, the faster they develop.  They must be brought inside for the winter as their development will slow considerably and they will die in a freeze. 
6. When the wheat bran particles start looking smaller and the layer gets thinner, add more (just dump it over everything).  I add more a few times a year.  I only clean up the dried vegetable matter that builds up, more rarely the bran.  
7.  Wait a couple months after setting up your colony before you begin using worms for food.  Use only the larvae (worms) to feed your birds.  The pupae and beetles should be left alone for reproductive purposes.  There is no need to remove dead animals, old carcasses will be consumed by successive generations.  You can collect worms when you add new food.  For example, cut a potato in half, put the cut side down and wait 10 min. or so. The larvae will grip on with their mouths and you just lift them up and shake them into a container.  Remember, they are harmless and don't bite. 
8.  Some people separate beetles, pupae and larvae--I don't, mostly because production is fine for me without the extra effort.  If you provide adequate resources for the colony, cannibalism is very low.   However, separating them is a good way to observe development--which is very interesting.
9.  Because reproductive and developmental rates are higher with greater temperatures you'll often have more worms in the summer than winter.  You can extend the summer glut of worms by packing them in fresh bran and storing them in the refrigerator for later use.
A word of caution:  With prolonged or frequent exposure to mealworms, some individuals will develop severe allergies to them.   I highly recommend wearing a mask while tending to your colony and be observant of any respiratory changes you might experience while working with it.   
This colony has been in continuous operation for several decades; I have been caring for it since 1987.
larvae and pupae


Comments (211)

What a great and easy-to-follow guide! Thanks so much for posting this, I'm starting mine today!
I really am interested in doing this. Where do I get mealworms?
Check the mealworm thread in the Feeding and Watering section. Several folks there sell them. WestKnollAmy is probably the most active. You can also find them at your local Walmart or pet store.
how long before a meal worm turns into a beetle.
How long to hatch a pupae?
thanks in advance
just found it thanks a bunch
Just wondering... How many meal worms can live in a 10 gallon tank? 100? 500? 1000?
I've never counted, but I would guess that there are between 10,000 and 20,000 in the pics above.
Okay, thanks! Do you think a 6" by 12" container would work for 500 then?
I just got started a couple days ago with 200 worms. I might pick up more to boost it but I'm off to a start.
I found some totes and am ready to start my experiment, does the lid need to be TIGHT fitting, or not? if it's tight, should I drill any tiny ventilation holes in it??
I would recommend going without a lid entirely, if that is at all possible. The more air circulation that you have, the better off the colony will be. If you absolutely need a lid (perhaps to keep out a cat), then drill as many holes as possible. I also have a colony in a very large tub that didn't have a cover to keep out wild birds and lizards. I fashioned one out of a piece of hardware cloth by bending the sides down. Good luck with your experimenting!
that was ridiculously simple-sounding. Hmmmmm, even a silly nurse like me may be able to do this. I love it!
I've hunted forever for a simple and easy-to-follow guide..this is it! Thanks you, thank you, thank you! I'll be getting started soon and my 20 chickens will be so happy!! this site has tons of great info on raising your Melaies. Mine came today and I have them all set up, looking forward to this. It will be so fun and the chickens will benefit greatly.

Hi, I just ordered my meal worms (30 large). It seems like a small amount however I believe these will multiply quickly as I live in Brisbane/Australia and it is very muggy at present, winters are very mild. I only have 1 Silkie and will be getting 4 Australorps shortly.
Got my tank and wheat bran, just need to order the mealworms. Looking over all the sites on the internet to find the best price and quality. Any suggestions?
You can look for a list of suppliers on the first page of the Mealworm Farming thread. I'd recommend trying WestKnollAmy first.
Great info for a beginner like me. Can they be fed to chicks? Or should we wait until they are in the coop?
Yes, you can feed them to chicks---provided they have access to grit. They tend to have a hard time with the larger ones at first, so I give them the smaller worms.
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