Half eaten Morio Beetles

[Spinnennetz]

This is the first time I’ve witnessed this. I feed them veggies every other day or so for their water source, and I have a grain-based substrate. I also occasionally throw in a couple of dog/cat kibbles, some millet seed, and maybe a bird treat which could be nuts or dried fruit.

I have both pupae and beetles in the bin, and like I’ve said, this has never happened before. Believe it or not, all 3 beetles are still alive, which is why this is confusing to me.

I wanted to make sure there wasn’t any sort of other cause for this, like a pathogen, but I am assuming the other beetles munched on these guys. But wouldn’t these beetles run away, or be too weak to move/dead? From what I’ve read they usually only leave the head. They seemed as energetic as the rest of the beetles (hiding).

Should I cull the 3 beetles? (I’m assuming yes, certainly the half beetle)

Could it be from over crowding? There’s 80ish beetles/pupae in a single 10x15” bin