pupating at top of substrate?

[Regiarbol]

So recently one of my Dynastes granti larvae pupated, but it pupated on top of the substrate for some reason. Do any of you know a cause for this? The soil was a tad dry, but I've seen larvae pupate "normally" in the same or similar conditions. It didn't seem to have built a chamber either, and I found it one day just lying there.

(I'll be honest and say that I haven't been changing out the substrate as often as I should have, but I have been busy lately.)

 

[GeneralZero]

It probably just didn't find the substrate suitable enough or even well moist enough to pack down.