# Mealworm Pupae Dying



## Danvie (Sep 12, 2017)

So I recently decided to set up a mealworm "farm". My mealworms are all full sized and many of them already became pupa. Problem is that none of them seem to be making it to a beetle. They survive a couple of days but then they just turn really squishy to the touch.. like really squishy. Sometimes if I try to pick it up I accidentaly do it too hard and all the inner juices come out... I'm not sure what's causing this problem either... I feed my mealworms oatmeal and carrots and I'm wondering if the oatmeal is too dry for them? I separate the pupa to mealworms in a different container and I also wondered if it was that they didn't have enough humidity so i put wet wool inside to see if it would help. Can the temperature be a factor? It's pretty cold here in Ireland especially in the night so I dont know if that affects it either


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## Nightstalker47 (Sep 12, 2017)

Danvie said:


> So I recently decided to set up a mealworm "farm". My mealworms are all full sized and many of them already became pupa. Problem is that none of them seem to be making it to a beetle. They survive a couple of days but then they just turn really squishy to the touch.. like really squishy. Sometimes if I try to pick it up I accidentaly do it too hard and all the inner juices come out... I'm not sure what's causing this problem either... I feed my mealworms oatmeal and carrots and I'm wondering if the oatmeal is too dry for them? I separate the pupa to mealworms in a different container and I also wondered if it was that they didn't have enough humidity so i put wet wool inside to see if it would help. Can the temperature be a factor? It's pretty cold here in Ireland especially in the night so I dont know if that affects it either


How cold? Temperatures are definitely a factor. I have had success breeding mealworms before. I kept them in the upper to mid 70s range. They seem to pupae and turn into beetles quicker when the temps are somewhat elevated.


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## Danvie (Sep 12, 2017)

Nightstalker47 said:


> How cold? Temperatures are definitely a factor. I have had success breeding mealworms before. I kept them in the upper to mid 70s range. They seem to pupae and turn into beetles quicker when the temps are somewhat elevated.


Just under room temperature. How do you keep yours heated?


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## Nightstalker47 (Sep 12, 2017)

Danvie said:


> Just under room temperature. How do you keep yours heated?


I use a space heater. Room temperature varies greatly depending on where you are situated, what are your temps?


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## Danvie (Sep 12, 2017)

Nightstalker47 said:


> I use a space heater. Room temperature varies greatly depending on where you are situated, what are your temps?


Well I just placed them inside of this... thing that keeps the heat in. not exaclty sure what its called but i maintains steady temperature... In the night I'm guessing 15 degrees celcius


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## The Grym Reaper (Sep 12, 2017)

My gaff is old as heck and probably has cack insulation but I don't think it drops much below 18°C in my room with the heating off and I've had no problems breeding them.

I just keep the pupae in an empty container until they moult out into beetles and then I place the beetles into a well-ventilated container with just oatmeal substrate and leave them to mate/lay eggs until they die off.

I don't keep the beetles and pupae together as the former tend to eat the latter.

Reactions: Agree 2


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## boina (Sep 12, 2017)

Danvie said:


> So I recently decided to set up a mealworm "farm". My mealworms are all full sized and many of them already became pupa. Problem is that none of them seem to be making it to a beetle. They survive a couple of days but then they just turn really squishy to the touch.. like really squishy. Sometimes if I try to pick it up I accidentaly do it too hard and all the inner juices come out... I'm not sure what's causing this problem either... I feed my mealworms oatmeal and carrots and I'm wondering if the oatmeal is too dry for them? I separate the pupa to mealworms in a different container and I also wondered if it was that they didn't have enough humidity so i put wet wool inside to see if it would help. Can the temperature be a factor? It's pretty cold here in Ireland especially in the night so I dont know if that affects it either


No - the moisture is the problem. Pupae need to be completely dry to pupate - or at least I keep mine completely dry. Mealworms in general don't handle too much moisture well. Mine are kept on oatmeal that gets supplemented with _small _pieces of fresh veggies and not even every day. I take the pupae out and place them on pure, completely dry oatmeal for the beetles to find something to eat when they've hatched. Once a week or so I transfer the hatched beetles to the beetle box. They breed like crazy - I feed the surplus worms to my rats who love them.

Reactions: Agree 1 | Helpful 2


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## The Grym Reaper (Sep 12, 2017)

boina said:


> supplemented with _small _pieces of fresh veggies and not even every day.


I don't bother at all, they don't seem to need them.


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## boina (Sep 12, 2017)

The Grym Reaper said:


> I don't bother at all, they don't seem to need them.


Come on, think of all those vitamins  - must be good for something


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## miss moxie (Sep 13, 2017)

The Grym Reaper said:


> I don't bother at all, they don't seem to need them.





boina said:


> Come on, think of all those vitamins  - must be good for something


Not only that, but think of enhancing the flavor! Mmm, corn flavored mealies for the Ts! Then some mashed potato flavored ones and finally a little roast beef flavored ones. 

I think I'm just hungry.

I didn't do anything fancy and my meal worms pupated and turned into beetles. I just left them in the packaging they came in directly from the seller and then transferred the pupae into a tupperware container with ventilation and wheat bran. They're all beetles now.

Reactions: Cake 1


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## The Grym Reaper (Sep 13, 2017)

miss moxie said:


> Not only that, but think of enhancing the flavor! Mmm, corn flavored mealies for the Ts! Then some mashed potato flavored ones and finally a little roast beef flavored ones.
> 
> I think I'm just hungry.
> 
> I didn't do anything fancy and my meal worms pupated and turned into beetles. I just left them in the packaging they came in directly from the seller and then transferred the pupae into a tupperware container with ventilation and wheat bran. They're all beetles now.


I haven't had many, if any, die off in the larval stage so they obviously don't need the extra moisture.

I just have them in this (ventilation is in the lid to prevent escapes), I either keep them in my room or the fridge depending on how many beetles/pupae I have, I'm curious as to whether or not I can use my roach chow (ground up dog biscuits + fish food + vitamin/calcium
powder) as substrate, I might just try it and see how I get on.




As already mentioned, the only problem I've had is beetles eating pupae if not separated.


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## miss moxie (Sep 13, 2017)

@The Grym Reaper You could always try separating out a test group into a small enclosure and seeing how they do on the roach food. For science.

Reactions: Funny 1


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## boina (Sep 13, 2017)

Mine do get fish food for added protein - they love that. I think even my meal worms are spoiled

Reactions: Funny 1


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## miss moxie (Sep 13, 2017)

boina said:


> Mine do get fish food for added protein - they love that. I think even my meal worms are spoiled


No harm in pampering them before they meet a grisly end.

Reactions: Funny 2


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## The Grym Reaper (Sep 13, 2017)

miss moxie said:


> @The Grym Reaper You could always try separating out a test group into a small enclosure and seeing how they do on the roach food. For science.





boina said:


> Mine do get fish food for added protein - they love that. I think even my meal worms are spoiled


I'll give it a blast then, the dog biscuits are mostly made up of cereal iirc.


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## richard22 (Sep 21, 2019)

boina said:


> No - the moisture is the problem. Pupae need to be completely dry to pupate - or at least I keep mine completely dry. Mealworms in general don't handle too much moisture well. Mine are kept on oatmeal that gets supplemented with _small _pieces of fresh veggies and not even every day. I take the pupae out and place them on pure, completely dry oatmeal for the beetles to find something to eat when they've hatched. Once a week or so I transfer the hatched beetles to the beetle box. They breed like crazy - I feed the surplus worms to my rats who love them.


This issue is the same for me across many attempts in different seasons and produce. I read elsewhere it might be the LACK of moisture that causes the pupa death. Honestly I don’t think it is moisture since this pupa death isn’t really common issue for breeders. An entomologist told me it might be CO2 or lack of ventilation, but I did trials with some mealworms in a few sterilite containers and several pupa became beetles, and ironically the ones I didn’t feed new produce had the most pupal success. This means the moisture couldn’t have been a factor, I left old black banana peels and collard greens that dried out and they had more success than the potatoes and carrots. These trials also had no ventilation and I rarely switched the food out, but I got maybe 10 beetles from ~150 mealworms so it kindof worked, a lot better than the attempts in open containers.

Grain mites don’t seem to be a problem in my specific mealworm bins, but they did invade my superworm bin and presumably ate all the eggs the beetles laid. 

The entomologist told me it might be colony cross-contamination and/or zootic disease of some sort. I don’t know what that could be though. I do use the same gloves for all my colonies, but now I started using latex for the mealworms and a thicker one for my roaches and crickets. On top of the browning, most of the mealworm pupa that don’t brown become deformed. I theorized it could’ve been pupal disruptions, but this issue would be a huge concern for mealworm breeding if it were this much of an issue, which it isn’t for most breeders who probably don’t care much how they treat the pupa as they aren’t told they need special requirements to hatch, meaning they CANNOT need special requirements to hatch. I had great success with my first mealworm batch which made many beetles a year ago, but after the 2nd gen worms every worm has gone the same path except in rare cases or somewhat commonly in the trial experiments. I did start using potatoes last year, but I tried mealworms with a bunch of organic and non-organic produce and the most success was without fresh produce and basically with neglect. I started using wheat bran, but I doubt that could be a concern as it is very commonly used without issues organic or not. I also doubt it could be isolation concerns, because this issue is ONLY brought up with superworms and if it were a real consideration the breeders would speak of the issue much more often.

My superworm pupa have been suffering from this same issue to a slightly lesser extent, and to a significantly lesser extent to my micro and lesser mealworms too, who I don’t isolate pupa.


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