I will note I have obtained these worms from my local pet store, but the first generation which was in August 2018 all became beetles with a few mutated individuals once and awhile but it is negligible and they were indeed from the store. I have looked across the internet for info on this but could not find any conclusive or even usable information. Recently as spring has come, some of the pupae are Almost getting there, but they are trapped in their shell and if they do turn into beetles they become mutated and very limp, discolored, and their abdomen looks very empty. I know it can’t be the substrate or light because I have had a few separate batches in different grains and locations. Or humidity because it would correlate to the seasonal change. I suspect this to be related to conditions, like room temp. I have had only two successful beetles from probably hundreds of mealworms. Almost all of the pupae have failed to pupate, most of which turn a hue of brownish orange and slowly die and turn dark brown or black and brittle.

I have had very little success with my 2nd generation of mealworms for a couple months now since autumn.

Download pupating mealworms