Darkling beetles / mealworms beetle lifespan?

[zaxon]

Hey! I have been breeding mealworms, I currently have two tubs of about 1000 worms in each. I have one tub which has about 150 Darkling beetles (adult stage of mealworm). I used to have over 200 but Some have died off over time. My beetles have been alive, in the adult beetle stage, for about 4 months, and I just found out they are only supposed to live for about one month... I'm so confused and I don't know what I'm doing that's so right hahaha. I realise that some have died, but there are over 100 still alive and healthy, and mating