One larva, one pupa and one adult shown.

I broke open several mature puffballs, finding a number of inner nodules I suspected were tiny beetle grubs or pupae. In fact, I saw several grubs or pupae (I couldn't tell which without aid of magnification) while stirring and rubbing the spore dust and nodules. I saved the dust, nodules, etc. in a pill vial and re-examined it the next day, finding several very dusty mature beetles, one pupa and one grub. I'm assuming for now they are all the same species, but will see if the grub and pupa agree on maturation. I was impressed at once with the unusual antennal structure of the adults,

I think the beetles are designed to carry a thick layer of spore dust around with them so that, when they freeze motion, they are hard to detect amid the puffball contents.