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Hi all,

I have some Chrysina gloriosa that I think are starting to pupate-- I only think that cause there is a racetrack around the top of their circular enclosure where presumably the grub was wandering.

Should I leave them alone till I see beetles or can I inspect to see if I can find pupa in substrate?  Also, how long does the pupal stage typically last?

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4 hours ago, Yellowfin2na said:

Any changes with yours?

Mine are still doing the same, I've read that this is normal behavior prior to pupation but i put clay down at the bottom in hopes that they would be satisfied when they found it and pupate rather than wandering forever 😢

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Please describe the containers (dimensions and volume, and ventilation level) you are keeping the larvae in, and details about your substrate (e.g. - your clay soil layer's density and moisture level, and the thickness of the layer).  How long have the larvae been wandering at the top?

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Not trying to hijack the thread, but here is my container for one larvae (gloriosa). Substrate is slightly moist enough to hold shape. But not wet enough to show humidity on the lid of the container. I don't have exact dimensions so the pen is for scale. Wondering has occurred the past two or three weeks.

I do have some woodii in container about twice this size with a clay bottom. Due to the wet clay the flake soil is quite wet with humidity spots on the lid. They also seem to wonder quite a bit.

Examining woodii and gloriosas natural habitat from my understanding is a pretty dry area of west Texas. 

160230455239925328.jpg

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One more thing.

I have 9 different containers of all sizes and 12 total Chrysina larvae. Each container is slightly different when it comes to humidity but all have flake soil. Two containers have clay with flak soil on top and the rest have just flake soil. Almost all larvae are L3 and there is wondering tracks in every single container. 

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A slightly compacted layer of clay soil (at least a couple of cm thick) needs to be placed at the bottom of the containers for Chrysina, otherwise they won't make pupal cells.  Without the clay, they will typically wander indefinitely until they eventually wither away.  The flake soil layer should be full to the top, in contact with the lid, to create the pressure needed to make the larva feel like it's at a secure depth.  A container for a single larva doesn't need to be any larger than 8 or 9 oz.  Even 5 oz is adequate.  The use of really large containers is best avoided, since in this case it's harder to control the humidity level of the clay layer over time (after cell construction, too much moisture can gradually seep down into the clay from the flake soil, over a period weeks to months).

The flake soil should be quite moist (the same as that used for Dynastes spp. and other rhino beetles).  Chrysina are from high altitude, mountain environments where the soil remains rather moist.  The substrate should be moist, but certainly not soaking wet, of course.  Excessive moisture will cause pre-pupae / pupae to rot, but excessive dryness will dehydrate them.  After cell construction, there will be a long diapause as a larva (over the fall / winter months), followed by the pre-pupal stage, and then a rather short pupal stage.  Following eclosion, the adults will remain in their cells for a while, like most beetles do.

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As with anything of course, it's a bit difficult to adequately describe the rearing process using only words (or even photos and video).  I can give advice, but it's no substitute for actual experience.  I've been keeping Chrysina for many years, but have only just in the past several years really come to understand their requirements enough to be truly successful with them.  In some ways, they're just a little more complicated than some other species in respect to the particular environmental conditions needed for the pupal cell stage, but among Chrysina's advantages are that they really don't require very much space, resources or care, compared to some other things.  Also, even one female can produce a LOT of eggs, so even if you have only one pair of adults, you can end up with all the larvae you need to start up a new generation - often, far more than you'll need, actually!

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When you say long diapause how long are we talking? Several months?

Yes - months.

Will this occur even if they are kept indoors at normal room temperature (71-74 degrees)?

Yes.

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This is what I put together. These are 10 oz containers. Bottom is lined with moist clay. Containers filled over the top and then compressed with the lid to create a suction effect like you said. I moistened the substrate quite a bit since it seemed very dry based on your instructions. Since I was switching containers I went ahead and weighed all of them to see if there has been growth in the past week. Almost all of the Woodii gained nice weight. The gloriosa did not gain much. The substrate in the gloriosa container was much drier. Here are the weight gains along with photos of the new containers.

@ the_cream_man sorry again, not trying to take over your thread man... I just think it is all relevant information. Post what you have as well because I think we can all learn from each other.

Weights

C. Gloriosa                                                       

LARVAE A                                          

09/28       2.0 g                          

10/10        2.1g                             

LARVAE B                                          

09/28     3.1g

10/10      3.1g

LARVAE C

09/28     2.2g

10/10      2.4g

C. Woodii            

LARVA A

10/3     3.8g

10/10    4.5g

LARVAE B1

10/3     2.7g

10/10   3.4g

LARVAE B2

10/3     3.2g

10/10   4.2g

LARVAE C1

10/3      2.9g

10/10     3.4g

LARVAE C2

10/3      4.6g

10/10     5.2g

LARVAE D1

10/3      4.1g

10/10     4.6g

LARVAE D2

10/3      3.9g

10/10     4.5g

LARVAE E1

10/3      2.8g

10/10    3.6g

LARVAE E2

10/03     4.1g

10/10     4.4g

 

Larvae's D1,D2,E1, and E2 where in 20oz containers with clay and flake soil. 

Now they are all in flake soil with clay bottom.

 

1206691219_160230455239925328(2).jpg.bbe4d03382014f19e224afb04c94f72a.jpg

160230455239925328 (1).jpg

160230455239925328 (3).jpg

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On 10/10/2020 at 5:18 PM, Yellowfin2na said:

@ the_cream_man sorry again, not trying to take over your thread man... I just think it is all relevant information. Post what you have as well because I think we can all learn from each other.

 

No worries, seriously thank you for keeping the thread alive!!  Idk why but I haven't been getting notifications on it-- every thing you've posted is very relevant to me as well!

From what's been posted I'm starting to think my issue is that my tubs aren't full to the top-- 

@Goliathus, My larvae are each in a 16oz deli cup and unfortunately I have absolutely no spare flake soil.. how critical is the pressure requirement and would it be better for me to put multiple in one container and reuse the substrate to get a few full? I do have some flake soil early on in the process of fermenting-- should I pack the top with that just to get the pressure even if they can't eat it?

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17 hours ago, the_cream_man said:

No worries, seriously thank you for keeping the thread alive!!  Idk why but I haven't been getting notifications on it-- every thing you've posted is very relevant to me as well!

From what's been posted I'm starting to think my issue is that my tubs aren't full to the top-- 

@Goliathus, My larvae are each in a 16oz deli cup and unfortunately I have absolutely no spare flake soil.. how critical is the pressure requirement and would it be better for me to put multiple in one container and reuse the substrate to get a few full? I do have some flake soil early on in the process of fermenting-- should I pack the top with that just to get the pressure even if they can't eat it?

Just thinking out of the box here...... if you do not have any spare flake soil could you just thicken the clay layer at the bottom until your flake soil reached the top? I imagine thickening the clay layer should not make a difference because I am sure in the wild the clay layer is extremely thick. What do you think Goliathus?

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Yellowfin2na
This is what I put together. These are 10 oz containers...

Those boxes are only 10 oz?  They look much bigger.  This is quite different from the type of set-up I use for rearing / pupation of Chrysina spp.  I'll see about posting some photos of mine later today.  There are probably numerous ways of doing it right, as well as a nearly infinite number of ways of doing it wrong, of course!

the_cream_man
...My larvae are each in a 16oz deli cup and unfortunately I have absolutely no spare flake soil.. how critical is the pressure requirement and would it be better for me to put multiple in one container and reuse the substrate to get a few full? I do have some flake soil early on in the process of fermenting-- should I pack the top with that just to get the pressure even if they can't eat it?...

Yellowfin2na

Just thinking out of the box here...... if you do not have any spare flake soil could you just thicken the clay layer at the bottom until your flake soil reached the top? I imagine thickening the clay layer should not make a difference because I am sure in the wild the clay layer is extremely thick. What do you think Goliathus?

Yes, you could thicken the clay layer, but in the interests of maintaining the right moisture level in the long-term, it might actually be better to just add some moistened, raw (non-fermented) sawdust to the top of the containers to fill them completely, if you have no extra flake soil to spare at the moment.  The raw sawdust shouldn't harm the larvae - if they find the non-fermented particles to be inedible, they just won't eat them (although, like the clay layer, they may mix them up with the fermented material to some extent).

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15 minutes ago, Goliathus said:

it might actually be better to just add some moistened, raw (non-fermented) sawdust to the top of the containers to fill them completely, if you have no extra flake soil to spare at the moment.

I've just filled them to the top! Hopefully in the next few weeks I start seeing some pupal cells :)

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20 hours ago, the_cream_man said:

@Goliathus, not super related but my D.tityus also do not have substrate to the top of their container- should these be packed too?

I've found that tityus larvae, if making pupal cells in small containers that aren't completely filled, will usually pack the substrate to one side so that it's firmly in contact with the lid.  Chrysina larvae sometimes do this too, though it seems that they feel more secure if the substrate is filled to the top to begin with.  A less than full container might possibly lead to excessive wandering, especially when they're preparing to make cells.

Here's a photo of my woodi rearing / pupation containers (5.5 oz).  I used 9 oz containers in previous generations, but they grow and make cells in the 5 oz just the same.  I have 80 of them stacked in a 10 gallon tank.  As you can see, they've mixed up the clay layer with the flake soil rather thoroughly.  It's been nearly 6 weeks since I added the clay.  I'm not sure how many of them have made cells yet - maybe around 40-50% - 

woodi_cont.jpg

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2 hours ago, Goliathus said:

Here's a photo of my woodi rearing / pupation containers (5.5 oz).  I used 9 oz containers in previous generations, but they grow and make cells in the 5 oz just the same.  I have 80 of them stacked in a 10 gallon tank. 

 

Thanks for sharing your set-up!  Do you have any ventilation holes in these at all?  Also, love that you've got it down to 5oz cups, I thought I was pushing it with 16oz!

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Man those look great. If those are 5oz then I guess my containers do look larger than 10oz. I came up with the 10oz by taking measurments and using a volume calculator.

None of mine are mixing the clay with the flake soil from what I can see. 

Out of the 80 how many are you expecting to fail pupation?

 

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the_cream_man
Thanks for sharing your set-up!  Do you have any ventilation holes in these at all?  Also, love that you've got it down to 5oz cups, I thought I was pushing it with 16oz!


Yes - 5 pin holes for ventilation, in the lids.  This prevents the entry of fungus gnats, and allows for passive enough ventilation that the substrate won't eventually dry out over a period of months.  Some exchange of air also slowly occurs at the junction of the cup and lid, since these containers don't actually seal completely air-tight.

the_cream_man
ALSO:
omg!  I just checked and it looks like I already have one forming a pupal cell-- I think the pressure was a winner for sure :)
(The picture didn't come out well so I upped the exposure to show the soil discoloration around it)


Yes - when you see that the larva has created a hollow and there is a noticeably dark ring around the edges, that's usually a good indicator that it has settled down to make a pupal cell.  C. beyeri and gloriosa nearly always use the container walls as one side (and/or the bottom) of their cells, but woodi usually makes a fully enclosed cell.  In smaller containers though, woodi will use the walls more often than if in a more spacious area.

Yellowfin2na
Man those look great. If those are 5oz then I guess my containers do look larger than 10oz. I came up with the 10oz by taking measurments and using a volume calculator.

None of mine are mixing the clay with the flake soil from what I can see. 

The size of the containers definitely has an influence on how much they mix together the two substrates.  In 16 oz cups, the mixing isn't always as thorough.  But, mixing it all together doesn't seem to affect larval growth, and anyway, by the point at which I add the clay soil, the larvae are pretty much at full size and nearly done feeding.

Out of the 80 how many are you expecting to fail pupation?

In the previous generation (9 oz containers), I had less than 10% pupation failures.  I'm hoping for a similar result with the current group.  Interestingly, I also reared a couple of groups (woodi) together in 10 gal. tanks, and had a huge die off of pre-pupae / pupae.  What few beetles did manage to survive and eclose in that type of set-up, were mostly badly malformed.  I suspect that too much moisture gradually seeped down into the clay layer, where the pupal cells were built.  That's why I'm now rearing Chrysina larvae individually in small containers - it's a lot easier to keep the humidity within a certain range this way.  I think that any container of 16 oz or smaller should be ok.  It's only in something considerably larger, with a lot of substrate depth, where excess moisture issues can occur.  Even if the moisture level of both the flake soil and clay soil seems ideal when you initially set it up, unfortunately, moisture always gravitates downward eventually, and in a large-sized enclosure, the ultimately leads to drier flake soil sitting on top of a clay layer that's absorbed a lot of the moisture that was originally evenly distributed in the substrate above it.

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