Mealies Not Pupating + Pupae Deaths

[Neon Aurora]

My colony of mealworms has grown quite large and the worms are quite large themselves. I haven't kept track of how many weeks old the batch in question is, but it feels like it's been a really long time (months) and barely any of them have pupated and I'm starting to find some dead worms. My older beetles are starting to die off now and I have barely any pupae to replace them. Why could this be happening? They live in a base of wheat bran and are provided with fresh fruits or veggies maybe once every other day (no exact schedule). Lately their staple has been cooked yams but they also get potatoes, apples, carrots, or whatever else I happen to have. For a while they were getting fermented wheat bran as well but I have fallen behind in that (want to start up again soon). They are very large and very healthy worms. Does anyone know why they aren't pupating?

I have noticed the pupae and beetles from this batch are almost twice the size of my previous batch. I'm assuming this is just because I figured out how to keep them healthy and make them grow better and isn't harmful, but I thought I would mention it.

Secondly, about half (maybe more) of the ones that do pupate (I maybe find 2 every week if I'm lucky) are dying a few days after. I find the pupae and remove them into a bin I have set aside for pupae, and I find them dead a few days later. This is the same bin in the same place I was using before and I never had so many pupae die.

Any input is appreciated. My colony was doing so well, I had more worms than I ever needed but now I'm getting worried.

 

[DrCarrotTail]

Have your temps gone up with the summer weather or do you have more worms than before in the bin making it heat up? Aside from heat I think some of my mealies will snack on the pupae if they don't have enough moisture. Too much moisture can also kill them. Good news is that each mature beetle female makes a couple hundred eggs so you shouldn't be lacking for new baby worms even if only half of the pupa make it to the beetle stage.

 

[Neon Aurora]

The house is always pretty cool, but I do have quite a few worms (honestly way more than I need) so I suppose the number of worms could be a factor. I only found a few dead ones, so I don't think the bins are too hot. I'm more concerned that they don't seem to be pupating.

They definitely have enough moisture. I've been feeding them a ton of fruits and veggies because they were looking kind of crappy (not growing well and not getting nice and plump and staying active).

I was wondering. Can having an abundance of food delay their need to pupate? I was thinking that in nature, they hatch from eggs and eat through their food supply. When they've eaten all the food, they pupate, turn into beetles, and disperse to find food elsewhere. Could my feeding them tons be making them stay worms longer?

 

[DrCarrotTail]

I do think they wait a bit longer to pupate if they are well fed. It gives them more of a reserve to make it through the pupal stage and more energy reserves once they make it to their adult form. Mealworms will eventually pupate though. Superworms will stay larvae for as long as they have food but mealworms will change once they hit their max size. A lack of food, however, can make them pupate early.

 

[Neon Aurora]

I see. So it seems like what is actually going on is my worms that are now beetles were malnourished and pupated early. Now that these worms are getting more food, they are growing to max size and pupating at the optimal time. The few new beetles I do have are twice the size of my current beetle colony. I assume that is how big they are supposed to be and I was just doing a crappy job raising the worms. =P