Whatever happened to the mealworms?

Adult and juvenile

Adult and juvenile Tenebrio molitor… and a cauliflower stalk

Well, that was a question that I had been asking myself too. You may remember that I was having a go at raising mealworms as a source of protein-rich food for my hens (details here). I’ve been very quiet on the subject recently because I thought that it hadn’t been successful and I was looking at other options, However, I am pleased to report that the lack of success was only because I hadn’t been patient enough. I decided to tip the contents of my three mealworm tubs into a bucket last week with a view to feeding the contents to the chickens and giving up. However, disturbing them like this revealed much more life than I had thought remained.

Never having had a go at this sort of thing before, I knew little about the ecology of Tenebrio molitor, the species in question, so I wasn’t sure what to expect. I think I may have been wildly optimistic about the speed of the lifecycle… a salutary point about doing your research first! I’ve now done more reading:

The life cycle of Tenebrio molitor is of variable length, from 280 to 630 days. Larvae hatch after 10-12 days (at 18-20°C) and become mature after a variable number of stages (8 to 20), typically after 3-4 months (at ambient temperature) but the larva stage can last up to 18 months (Feedipedia)

All the life stages seem to be present now

All the life stages seem to be present now

So, the fact that I was not seeing large larvae as soon as I expected after raising the adults was certainly because it was too soon. My newly disturbed bucket, in fact, contains lots of mealwormlings, as well as live and dead adults, large larvae and a few pupae. They are currently feeding on rolled oats and gaining moisture from pieces of potato and cauliflower.

In addition, I discover that

Commercial mealworm producers sometimes include a juvenile hormone into the feed to prevent the larvae from molting into adults, resulting in “giant” mealworms that can achieve a length of 2 cm or greater and weigh more than 300 mg (Feedipedia)

A range of sizes of larvae

A range of sizes of larvae

Meaning that I may not be able to produce the big chunky mealworms that are available to buy from pet stores.  I don’t really mind this, because the hens are not fussy about the size of their food! And I suspect that the size issue is important for producers of dried mealworms, because they are bound to shrink with the loss of water as they are dehydrated.

During my recent research I discovered that the species is also known as ‘Darkling Beetles’, which sounds rather romantic to me. Plus, I was amused to read on one site:

Tenebrio molitor larvae are easy to culture (they are often raised on oats, and females lay up to 500 eggs), high in protein, and readily available commercially, so are a good food source for pet owners

But personally, I don’t fancy snacking on them myself!

Anyway, I will continue to care for my colony and see if I can viably produce enough to replace some of the chickens’ feed.

Leave a comment


  1. Sure the chickens will love them, definitely not for their pet owners!

  2. Glad it worked out. And good to know for when I have chickens (I will have chickens some day).

  3. Perhaps mixed with your morning porridge? …… ‘The oaty flavour of the mealworms enhance any breakfast cereal choice plus add your daily protein requirement in just one wriggly tablespoon……..’

  4. Hmmm, protein for the masses! Stir fried with fresh garden greens, or dried and used as a protein booster in otherwise meat-free dishes? I suspect you’ll be passing on that one, eh? Our worm farm died in the recent heatwave. There’s nowhere we can keep it below 30C on a permanent basis, everywhere just gets too hot, and we only cool the room we’re in at the time. I refuse to share the bedroom and living room with the worm farm, so it all got too much for them. Never mind, we have a bucket of concentrated worm tea and a polystyrene box full of worm castings. When I plant out my trees in autumn (couple more months to go), each one will get a dose of both…

  5. If the chickens turn out to be less than keen you can always package them as ‘The Good Food Source for Pet Owners’ though why pet owners should get preference I don’t know. I demand equality !
    xxx Hugs Galore xxx

  6. Perhaps a handful popped into a green smoothie would be the way to go! 🙂 This is something I’ve thought of doing…breeding them, not eating them…. but never got around to. Like Kate’s worm farm, do they need to be kept in a cool place……where do you keep your bucket?

  7. It is morning and I am wanting breakfast. Trying to do some catch-up on my reader I see a photo of oats and what at first looks like raisins! Ah….now I see that I am looking at future breakfasts for the HENS!
    I love it that you do everything you can for those special girls.
    I am so happy that the worms are growing!

  8. Must talk about this at our next chicken co-op meeting. Really want to reduce reliance on bought in layers pellets which are largely soya based. Though ideally would not want to buy in oats either.

    Oats: A grain eaten by horses. Also Scotsmen. – Samuel Johnson.

    • The oats were a temporary measure when I realised things were actually happening and the mealworms were in need of food. If this works, the long-term plan is to feed them on bran, which our local watermill keepers have in abundance – not exactly a waste product, but certainly one of their less commercially viable outputs.

  9. This whole thing would gross me out, except I have a friend who grows worms in a box in his man cave, for the purpose of adding them to his compost pile. So, I’ve already gotten beyond the ick factor. I’m happy that you’re happy. 😉

  10. I have to admit that I would give mealworms a go if I had to. They would be easier for me to eat than something with big eyes that had character. I hear that they are quite tasty too. Not that I would ever try them unless protein was an absolute scarcity on Serendipity Farm (God help us!) but I am going to try an experiment to grow some for our chooks. Cheers for the interesting share. It’s never boring at Chez Snail is it?! Now bring on the dog poo composter! 😉

  11. Somehow, I did not know chickens ate bugs. City girl here. I may become vegetarian after all. I’ve grown worms for the compost and soil but never thought about what I eat, eats. Educational day here. Thanks for that.

  12. yummy! 😀


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