Mealworm Pupation Problem

I have had very little success with my 2nd generation of mealworms for a couple months now since autumn. 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 only two successful beetles from probably hundreds of mealworms. I suspect this to be related to conditions, like room temp. Or humidity because it would correlate to the seasonal change. I know it can’t be the substrate or light because I have had a few separate batches in different grains and locations. 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 have looked across the internet for info on this but could not find any conclusive or even usable information. 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. This generation that is failing isn’t all just the 2nd generation after the successful beetle batch and their offspring, because I did get another batch and also another types of mealworm (potato beetle and buffalo beetle) the former having lackluster success but still having those problems and the latter doing just fine and flourishing in the same substrates with the same food (generally, I sometimes do feed them potatoes, the buffalo beetles getting carrot more frequently). I replace the worms’ food (potatoes, and carrots for small cultures) every other day. I don’t know if potatoes could be a culprit because i have been feeding them the same stuff since August. I at some point introduced styrofoam into their diets but I don’t think i did so before they had the issues. The buffalo beetles are not consumers of styrofoam but are doing fine, but I doubt that’d be the problem. I contain my mealworms in plastic sterilite bins in a cabinet and the smaller ones on top near a window, and I used oats at first but then now contain them in wheat bran and feed them potatoes every other day removing the old slices. I highly doubt the wheat bran would be the problem, but I could test a small culture in just oats to test. If anyone can help me understand what’s going on it would really be nice because mealworms are indeed a livestock for me as a hobby and potentially for money and/or human consumption and I like how they are much simpler easier to raise compared to the crickets which always died off with disease for me. I include images of the pupae and a temperature gauge below.

Meal worms will not pupate when in groups, they tend to keep in the larval stage and then die off as they age too long in larval stage.
Temp looks pretty good as does humidity, so I'm thinking they weren't separated so they would pupate.

It's a rather strange ecology for a larval organism but in laboratories, where they are used for class work, the larvae are kept together no more than 1 month then they are separated into small groups in large containers so they will pupate.

Redhawk

Bryant RedHawk wrote:Meal worms will not pupate when in groups, they tend to keep in the larval stage and then die off as they age too long in larval stage.
Temp looks pretty good as does humidity, so I'm thinking they weren't separated so they would pupate.

It's a rather strange ecology for a larval organism but in laboratories, where they are used for class work, the larvae are kept together no more than 1 month then they are separated into small groups in large containers so they will pupate.

Redhawk

I thought that applied just to superworm species, not the regular meal worm.

Bryant RedHawk wrote:Meal worms will not pupate when in groups, they tend to keep in the larval stage and then die off as they age too long in larval stage.
Temp looks pretty good as does humidity, so I'm thinking they weren't separated so they would pupate.

It's a rather strange ecology for a larval organism but in laboratories, where they are used for class work, the larvae are kept together no more than 1 month then they are separated into small groups in large containers so they will pupate.

Redhawk

In his case they are pupating, I have also seen plenty of mealworms pupate in groups of 1K or more. I think its about relative density, in order to completely halt their cycle you need them literally an inch deep in all areas.

But anyways its hard for us to know why they are dying without knowing your specific care routine and food.

You say:
I know it can’t be the substrate or light because I have had a few separate batches in different grains and locations.

But it is very likely their food source more than temp or humidity. What is their source of water - just potato and carrot? That could be fine but it would depend on the grains in there with them.

I never separate my meal worms unless it is to spilt a bin to make another one, and then I just take half the contents out and move it to a new bin. Then I add food to make up the difference in both.

I suspect diet is to blame. I feed high quality dog food, 2 parts, to chicken layer food, 1 part, and alfalfa pellets, 1 part.  I water with water polymer crystals, and very occasionally add a little bit of vegetable or fruit matter.  I keep mine at room temperature, but if I want them to breed as fast as possible, I keep them a little warmer, say 80 degrees.

If anyone is still listening.  I am having a similar problem with mealworms my kid got last spring.  We have 3 (1 died a while ago).

They have been wiggling around in oatmeal with a diet of carrots since March and have not pupated (is that a word)? They lived in a 1 pound plastic spinach container until last week when I finally separated them.  They are now in plastic 1 cup disposable food containers with holes in the lids.  They live on a table in our living room.  The oatmeal is about 1/2 thick.  I switch out the carrots when they shrivel and the oatmeal if it gets some mold. We live in a place with mild weather.  Not often hotter than 80c colder than 50 c. It is humid.  Fuck it, the Bay Area in CA USA. We don't have AC and haven't had our heater in since we got them.

I would love it if they metamorphized and we have three creepy-crawly beetles.

tia

My mealworms pupated when all together but this second batch I bought is not. I probably got 150 pupa from my first batch of worms again never separating. But this batch are just growing large. I did move to a cooler room and wonder if that’s the problem

Mealworms seem to do best at a 73 to 76 f temp range. Over 80f and they seem to slow down.

Redhawk

My  Beatles are not  Repopulating what am I doing wrong?

I’ve started having pupa. I separated my first 4 yestaday n they were pale n moved on touch. Today they have hardened n seem life less. Are they dead?  Also what’s best why to keep pupa

Hello all!! I have done so much research on breeding these mealworms and seem have super success. I got all my mealworms from the pet store and kept them downstairs in a 3 drawer bin with oat and wheat bran and Cheerios crushed up and oats then a bit of cornmeal
I put in scraps of fruits and veggies! They love apples and carrots and strawberries but don’t seem to like potato as much
They have all gone into pupa stage at some point and then turn into beetles! I have like 7 or 8 beetles now
Over 60 pupas and over 100 meal worms! I keep the beetles in the top drawer amd when they lay their eggs they will drop down the mesh and into the second drawer I have for the meal worms and then the last bin are the pupas
Pupas need humidity to change so I put them on a wet napkin and in my bathroom where it heats up well and has humidity!!
I found when I keep my room between 70f to 85f they change fast and the only issue I been having is some are not going from pupa to beetle stage easily and look deformed lol
But I just feed those guys off and keep it going!!

I have mealworms. Only on my first generation (which most have made it through to beetle stage). I found that leaving the pupae spread out in a layer of oats instead of collecting them all in a plastic container like I was before means less of them go brown n die. My theory is that they need good airflow in the same way that tomato plants do.

Also regularly check for and remove decaying food detritus or dead pupae.

Not an expert, but my my success rate went up when I figured this out.