Death in Pupal Cell

PowerHobo

PowerHobo

Chalcosoma
FML with grub deaths lately... this is 2 of my 12 purchased larva gone within a week.

This one was a Chrysina gloriosa who had constructed what I believe was a pupal cell about a month ago; empty chamber larger than the larva up against the side of the container, thin almost black border around it, hard-packed almost like a dirt shell when I broke it open. It appears to be pretty well constructed. I've read that Chrysina sp tend to just hang out in their pupal cells without doing anything or actually pupating for quite some time, so I wasn't concerned. The only reason I even opened it was because the larva has always been very visible inside, and I could see that the entire body was pretty much black this time. Sure enough, when I dug it out it was fully unresponsive, limp, and deflated-looking (picture attached).

Substrate looks clean, zero mold, and almost no frass either. Decently moist.

Am I just going through a spot of garbage luck, or is there something I should be concerned about in the environment in which I'm keeping my larvae?

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PowerHobo said:
FML with grub deaths lately... this is 2 of my 12 purchased larva gone within a week.

This one was a Chrysina gloriosa who had constructed what I believe was a pupal cell about a month ago; empty chamber larger than the larva up against the side of the container, thin almost black border around it, hard-packed almost like a dirt shell when I broke it open. I've read that Chrysina sp tend to just hang out in their pupal cells without doing anything or actually pupating for quite some time, so I wasn't concerned. The only reason I even opened it was because the larva has always been very visible inside, and I could see that the entire body was pretty much black this time. Sure enough, when I dug it out it was fully unresponsive, limp, and deflated-looking.

Substrate looks clean, zero mold, and almost no frass either. Decently moist.

Am I just going through a spot of garbage luck, or is there something I should be concerned about in the environment in which I'm keeping my larvae?
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I have heard a little sand helps Larvae construct cells, but don't put in a lot.
 
Most likely it’s just bad luck, and yeah sand is only for flower scarabs (they go nuts over the stuff) don’t try giving it to other scarabs (besides dung beetles) as it won’t do anything for you, and may do something against you.

 
The Ultimate Guide to Breeding Beetles states that ruteline grubs are quick to die near or at pupation if kept or fed incorrectly. The book makes them sound somewhat delicate as grubs.

Also, I don’t think sand is useful for all cetoniines, since not all spp. may use it naturally. It can actually harm insects not adapted to deal with it by abrading the cuticle.

 
AlexW said:
if kept or fed incorrectly. The book makes them sound somewhat delicate as grubs.
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That's the part I'm concerned about. 2 of my other 3 C gloriosa appear to be constructing pupal cells now, and I'd rather they not meet with the same end. My general go-to in any situation where something negative is happening is "what am I doing wrong," so that's what I'm trying to get tabs on here. Unfortunately, as this is my first year with any larvae requiring a moist/decomposed substrate, I'm stuck constantly wondering if I'm keeping the sub too moist, or not moist enough.

For instance, the sub I usually get from BiC is almost black, whereas the moisture level I tend to keep it at has it a more noticeable brown. When I spray the surface of the sub every few days (it's very arid where I am) the color difference is very noticeable. However, the sub is definitely compactible, and if I spray it any more often I usually have significant condensation on the inside of the container.

Lately, I've also been wondering if I'm keeping the room too warm in general. I'm keeping it between 78-82F for fermentation purposes, but I'm not sure if that might be too warm for the larvae.

 
Chrysina in general are very tricky when it comes to pupation. Easy as larvae up to L3. They then often do not find conditions they like to pupate in, many of them do not even build a pupal cell and die, and those who do also die off.

Not quite sure what could be the perfect substrate for them. I had added really hard pieces of white rotten wood, and they just gnawed it into pieces, and did not use it to whole up inside, which I have seen with other species. Next time, I will add a layer of clay in the bottom, that sometimes does the trick for those who do not like to pupate. Sand is always a good addition, and I am not aware of it having caused problems with my scarabs, when I used it.

Good luck.

Cheers

Ben

 
I've not had great luck with C. gloriosa, with deaths as larva, as well as very short-lived adults. In my experience they are a tricky species and require a good dose of luck, so I don't think you're necessarily doing anything wrong.

 
arizonablue said:
I've not had great luck with C. gloriosa, with deaths as larva, as well as very short-lived adults. In my experience they are a tricky species and require a good dose of luck, so I don't think you're necessarily doing anything wrong.
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Aren’t most commonly kept rutelines naturally short-lived beetles?

 
In a way this is definitely making me feel a bit better to know that Chrysina spp are so finicky and I'm not just a horrendous murderer. On the other hand, it is unfortunate to hear that by all accounts I should expect more deaths if not a complete loss of all larvae (as I only purchased 4). BiC's prices are definitely fair, but with the combined cost of larvae and sub plus the high mortality rate, I don't know if I'll give this species another shot via purchasing. Rather, I'll likely try to collect some of them wild and see if I can get some larvae from them that way, and after I've more-or-less figured out successfully fermenting oak pellets.

 
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PowerHobo said:
In a way this is definitely making me feel a bit better to know that Chrysina spp are so finicky and I'm not just a horrendous murderer. On the other hand, it is unfortunate to hear that by all accounts I should expect more deaths if not a complete loss of all larvae (as I only purchased 4). BiC's prices are definitely fair, but with the combined cost of larvae and sub plus the high mortality rate, I don't know if I'll give this species another shot via purchasing. Rather, I'll likely try to collect some of them wild and see if I can get some larvae from them that way, and after I've more-or-less figured out successfully fermenting oak pellets.
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If you’re willing to buy the Ult Guide, Orin has some notes (beware pests, wood-based diet important) for Chrysina success. I have it but do not wish to plagiarize his whole chapter, of course :/
 
Of course, nor would I ask you to
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It's on the list. I've got his smaller books.

 
Hi PowerHoBo,

I was curious if your other 2 C gloriosa survived and pupated. Did you find a substrate that seem to help the situation? ie: clay, sand, etc.

Thanks for any updates.

 
One died, the other is still alive, still a larva. The one still alive is actually the smallest of the group, and was the first to build a cell. It hung out in there for over 4 months before I finally broke it out, assuming it had to be dead and just mummified or something by this point. Still alive, though. Of course, I likely doomed it to die now by breaking its cell after so long, I doubt it'll have the energy to construct another.

As far as the sub I only ever had them in oak flake from BiC, and all of them were able to construct some very pretty and durable cells with it. Breaking them open to dispose of corpses has required effort enough to make me confident that the pupal cells were good.

 
Thanks for the update.

Sounds like it's still sort of a mystery on why the other 3 died.

From reading old posts, it sounds like Goliathus has been very successful with C gloriosa. Any special tips regarding C gloriosa Goliathus?

 
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