PUPATION NATION

After a month of raising nine little ones, there is a sense of pride in what is happening.  It has been said that only 2% of caterpillars make it to maturity in the wild.  So, with any luck, our nine babies will achieve 100% success.  They have already mastered eating and pooping and growing.  Time will tell how they fare on this next round.

Pupa - Latin for doll.  It is the life stage of insects that undergo a complete metamorphosis in their transformation between immature and mature stages.  Many are familiar with the act of metamorphosis but if you are like us you have no real idea what exactly is taking place.  So, Nicole did a bit of research and this is what she found out. 

As the caterpillar goes through the larvae stage of eating, pooping and growing, juvenile hormones are produced and released to tell it when to molt.

Number Nine, pictured above, is preparing to molt again.  Sure hope he grows this time!

At some point, the caterpillar reaches its final instar, the juvenile hormone decreases and the caterpillar is stimulated to pupate.  At this point, it is no longer interested in eating and begins to wander and look for a safe place to complete the next stage of its development.

In the case of our Empyreuma affinis babies, they do laps around the large storage tote that they are currently housed in.  Due to their new desire to wander away form their food source, a cover with paper towels and some holes punched in it has been put on top.

Now that #1 has found his desired pupation spot, it is time to spin a silken cocoon all around himself.

For a while Nicole thought that the caterpillar's hairs just fell out and into the web.  But after spying on #1 one as he worked one night she learned that he was actually pulling them out and weaving them in.  Oh, and look!  #2 has found himself a spot to settle in for the change.

What happens next had Nicole quite concerned.

She wakes to find #1, motionless and legs up in his hairy net.  And he stays this way, for over 24 hours!

Is he dead? 

Was this a failed pupation? 

No, thank goodness.  This is the beginning of an amazing transformation.

Oh and look whose joined the party.  #3 has found a suitable spot. 

And, #2 has nearly completed what Nicole has dubbed the Active Building (pulling hairs to put in web) phase.

OK  Here is your warning.  The next few photos of #1 could be considered seriously creepy if the process wasn't so damn fascinating and amazing!

We'll put the sharing off for a few more sentences by telling you that before a caterpillar even hatches from its egg it possesses bundles of cells that are destined to be the parts of the winged adult it will become.  In the case of our babies, Empyreuma pugione - the Spotted Oleander Caterpillar Moth is what they will become.  These bundles of cells are called Imaginal Discs.  All of the parts needed to make a moth are there, waiting, lying dormant until the decrease in Juvenile Hormone kicks them into action. 

What happens next?  Well,  #1 completes his final molt and then...

Um....  he begins to  'melt' in front of our eyes.    <<< speechless>>>

The change happens quickly and yet subtly.  You almost don't believe your eyes as you are watching it.

Nicole was filming just seconds before because she 'thought' she saw something but then wasn't sure.  She went to review on the video camera and it had begun.  So, instead of returning to filming she just snapped a few photos here and there.

#1 will never again be that cute little spotted crawler but hopefully in adult form will make many more cute little crawlers.

The pile of hair and skin at the tail end is #1's final molt.  Still a few more of those tell tale white spots to be seen.

Hopefully, you are noticing the ongoing changes.  Yes, he has turned over.

Some of the phases have beautiful coloring.  The eyes are taking shape on top and the striping on front is the legs, antennae and proboscis of the soon to be moth.

The wings are on the side of the pupa.

And, now.... we wait. 

For about two weeks, this is what #1 will look like while mother nature continues to form the beautiful red-winged moth that will emerge and continue the cycle.

Meanwhile... back in Pupa Corner, #2 is heading toward the phase Nicole has now named Suspended Animation.

After the cat finishes pulling hair and inserting it into the web it goes into a slow dive, of sorts.  First the anal prolegs detach from the roof, then the thoracic legs and then the abdominal prolegs in pairs.  In the above photo, this little one is now only hanging on by two sets of abdominal prolegs.  Not long after...

SUSPENDED ANIMATION!

And not too long after that...

#2 on the left  #1 on the right

Oh and we said #3 had joined the party.  Well...

Not wanting to be left out, #3 drops in to change.

Meanwhile, someone else has started to make the rounds.  Welcome, #4 as #3 begins to 'melt'.

#3 is done and it seems #4 has found a suitable building location.

Is it cheating or just plain smart to mooch off of your neighbors web?

Well, there isn't really any time to consider it.  Mother Nature will do as she pleases either way.

As of this evening, this is what one corner of our caterpillar world looks like.  Three cats pupated and one nearly there.

And, what is going on with the other side of our caterpillar world?

Still lots of eating, pooping and growing.  Oh, and Number Nine finally grew and is now 3/4"!!!

Spotted Oleander Caterpillars... Fifth Instar moving on to Sixth Instar and... IT IS HAPPENING!

The time is growing near.  An inevitable change (a metamorphosis) will happen soon.  Twenty six days old.  Fifth instars.  Three have molted and are sixth instars and one is in process.

Empyreuma affinis.  Spotted Oleander Caterpillars.  The babies.  Our babies.

                                                        Spotted beauties.

Each with their own personality.  This one had a bit of a tail feather issue after the last molt.  Cute.

For the most part they spend their days eating and pooping and growing.  But they are different in their own ways. 

You are familiar with number nine who has developed quite the personality of wandering and getting himself into trouble despite his miniscule size (he's finally made it to 5/8 of an inch!).  Then there is number eight (smaller than the others yet larger than number nine x2).  Booger is a wanderer and can often be found traversing the edge of the top of the box or, on especially ambitious days, sitting on the table beside it basking in the sun and celebrating his freedom!  Big Boy is the largest and rarely picks his head up from the leaves.  Long John is the second largest in girth but the longest when he does a full stretch having reached an inch and a half in length.  Mr. C has a bit of a back-door issue and some trouble with frass elimination often walking around with one hanging out of his rear.  And while the rest of the gang just let their frass fall where it may, Mr. Neat has perfected the ability to grab it with is anal prolegs, chuck it off to the side and keep his area neat and tidy.   The last two Nicole calls the quiet twins.  They are about medium in size and maintain a pretty low profile.

As our little ones have continued to grow the macro photography of them has become a tad easier.  We have been able to start to more easily identify their 'parts' and to learn more about them.

In this shot, for example, you can see the Stemmata which are six pairs of simple eyes.  They look like an upside down smile.  Caterpillars cannot really 'see'.  Their stemmata detect changes in light intensity (because they are composed of photoreceptors or light-sensitive cells), but they cannot form an image.  Also, that 'spike' hanging down from his chin is most likely a shot of the spinneret where its silk glands are located.

In this shot you can see the cats segmented antennae.  There is one on each side just under the eyes (most obvious on the right side of the photo here).   Instead of using their eyes to find food, the caterpillar relies on its antennae.

A pretty decent view of the spinneret (hair sticking off of the chin) and the Maxillary Palps (projection at junction of spinneret with chin) which are sensory organs that direct food into the mouth as well as the segmented antennae.

Caterpillars do breath.  Spiracles are their breathing pores.  They are usually located one on the thorax and eight on the abdomen.   We've tried to highlight (with black arrow) what we think are the spiracles on our cats but they are hard to see.

One of the easiest cats to see this on is the Canna Leafroller.  The white dots are the spiracles, the webs coming off of them are the tracheae.  Also easy to see on this transparent caterpillar is the Dorsal Vessel (the dark line down the center of the back).  Instead of hearts, caterpillars (and other insects) have this vessel separated by valves called ostia.  Hemolymph gathers in the valves and is pumped from the abdomen toward the head.  The hemolymph continues to flow down through the rest of the body, until it gathers back in the chambers, repeating the process.  Hemolymph does not carry oxygen as blood does but instead carries nutrients and immune cells.

Another interesting feature on our cats is their feet.  The front (thoracic legs) seen in the above photo are jointed with hooks and are used to hold onto food.

Their abdominal and anal prolegs on the other hand have crochets (or small grasping hooks) that let them climb very well.

Nicole does not like to use the camera flash around the caterpillars very often but found a good opportunity the other day as one was molting because it seemed the stemmata were covered and therefore the bright light may not affect the little one too much.  This allowed for the great shot above of the prolegs  and a few others.

Freshly molted and preparing to fluff the hairdo.

And now it is time to do the cute little wiggle dance.

Yum.  Nothing like a mouthful of some freshly molted exoskeleton and hair!

While the others just keep on growing, we still have no idea what is going on with Number Nine.

Number Nine continues to attack the easier (top layers) of the leaves but will succeed at the whole leaf after others have had a go.  Lately he seems to be losing his spots.  Perhaps it is because he just molted although the others obtain brighter spots upon molting.  So, the mystery continues with this one.

Speaking of molting here is a recent shot that clearly shows the old head capsule coming off as the light shines through it.

Even the thoracic legs are show to be coming out of the old exoskeleton (hence the light shining through their tips).

To continue... the caterpillars increased size means that their molts are also easier to photograph.

A fresh and complete exoskeleton of Empyreuma affinis - the Spotted Oleander Caterpillar.

The head capsule shots are below.  For reference the head capsule is smaller than the head of a straight pin.

Rear Shot - You can clearly see the two sides (the left and right vertex) and the Coronal Sulcus (joint down the middle).  Those little hairs are called Setae.  They are very sensitive to touch and can also be irritating to predators.

The underside shows the mandible and other previously mentioned parts.

In this front shot you can easily view the Stemmata (eyes) and the Adfrontal Sulcus and Area (triangular section) and the Frontoclypeus (section just below the triangle).

Since we've focused so much on molting it is probably worth mentioning again that three of the babies are now sixth instars.  For a few days we were not sure if that meant they would soon be pupating (beginning their metamorphosis) or not.  Well, this morning, the answer was confirmed for at least one of the little ones.  As Nicole was carefully removing the cover on their home she noticed one in the upper corner had webbed itself in with silk.

Can you see the fine covering of sliken hairs?

Since caterpillars can be very vulnerable in this state and should not be disturbed Nicole has tried to leave him alone while still doing her best to monitor the situation.  Throughout the day more of his black body hairs have begun to leave his body and fill the web around him.  Eventually, all of them will come off and cover him.

Both a happy and sad situation ... for at least one of our little ones, THE METAMORPHOSIS HAS BEGUN!

Third Molt... Our Empyreuma affinis Babies Are Fourth Instars!

As of our last writing, the majority of the spotted oleander caterpillar babies had already begun the period of inactivity which indicates the beginning of a molt. 

During this period, their body is producing an enzyme that will dissolve the interior portion of what is soon to become their old skin.  Also, their old head capsule, although still on their  head like a mask, has also separated from their old skin in preparation for the crawling out. 

Knowing this, explains why we were able to see a change in the head area and also able to see the new hairs matted underneath the soon to be old skin.

How does a caterpillar know when to molt?  It appears that there is a chemical secreted from the brain.  This 'Juvenile Hormone' as it is sometimes called when referring to the larvae (caterpillar) stage, tells the body to do the same thing but make it bigger. 

One research study has found that what triggers this hormone is oxygen depravation.  It seems that although the caterpillars body can grow its respiratory system cannot and when the body begins being starved for oxygen, the brain triggers the release of the Juvenile Hormone and the molting process begins.  With that process comes a larger respiratory system.

Pretty cool, right!

Cat on top is still overstuffing (this is typically when we see the super bright neon orange color) and Cat on bottom minutes from molting.

Cat on top molted earlier (the hair length has become easiest way to know) and has begun devouring leaf his sibling is preparing to molt under.

Hey, don't mind me, I'm just busy trying to molt down here!

Darlene came home from work to see the cats new container and commented that they were moving up in the world.  While that is true, the reality of it is that the cats have all seemed to go their own way on this last molt and the normal swap the old for the new  just wasn't going to work.  So, a container big enough to hold the fresh cuttings for the already molted ones as well as the older cuttings that some cats were still molting on (because they should not be moved when molting).

As of this writing, number nine is still a third instar while his siblings have all reached fourth.  He's been gorging on the new leaves though an should molt tonight.  He is currently measuring a full 1/2" while his siblings are twice that size.  He's got a long way to go and it is curious just how the process of becoming the Spotted Oleander Moth will go for him.

Speaking of.... here's a compiled video of the molting process that Nicole put together.  Turn on your volume if you want to hear the music and enlarge it to full screen for better viewing.  Enjoy!