Identify my mystery food

Over the winter months my worm bin has become infested with these tiny invertebrates. I've ignored them up until recently as they don't appear to be doing any harm and they seemed too small to bother with. The other day however I decided to collect a few and offer them to my Cynops juveniles who I might add are particularly fussy eaters. It was a great success and every last one was wolfed down.

They're about 1cm long, 1mm thick and superficially look like tiny meal worms, however they don't have legs and their heads/mouth parts are tiny. They're clearly designed to live underground because they struggle to move, other than folding themselves up and flicking, on a surface.

Whilst they look like they have a tough exoskeleton it is in fact quite soft and delicate - easily squashed by tweezers. It has a rubbery texture and when together they'll stick to each other. Harvesting them is relatively easy - this pot took 5 minutes to collect.

Does anyone know what they are? Could they be the larval stage of some other insect? I'm thinking maybe a fly.

First impression is that it has to be some kind of fly larvae..possibly a gnat?

They are fly larve, the flys are black & bigger than house flys with large wings. I have loads of them in my worm bins.
Peter

They look dilectible. My Cynops morphs are sooooo jealous! You could keep a couple of them in a jar and see what they turn into. If it's some kind of beetle, they might even be cultur-able.

Grumpet thinks they are likely midges.

As I previous said they are fly larvae. I found them mostly in the sawdust/poultry manure from my quail and they left their pupae cases all over the place. They survive in the worm bins ok but I think sawdust mix would provide a better culture media.

Peter

I don't think they're beetles - beetle and weevil larvae usually have legs. I think Peter's on the money. However I would be very curious to know if you can culture them - new foods are always welcome.