In the last article, Rabbi Shmuel Waldman spoke about the amazing process of caterpillars molting in order to be able to grow. Now we will discuss the last stage where they don’t molt anymore; rather, they shed their outer skin and then change into a chrysalis/pupa. This is also an amazing process and to appreciate it, we will need more pictures than usual. From the pupa, they will miraculously turn into a butterfly. That will be next week’s article BE”H.
So, their hormones signal to the caterpillar to stop eating and it somehow “knows” what is coming next, so it looks for a proper place to hang on to. For this next process to take place the special Juvenile Hormone finally reaches a very low level, which then allows this new process to take place. Up until then, as long as there was too much of this hormone, it held back this process from happening, and the insect would just molt. So, now we are starting the main process of the caterpillar’s transformation into a butterfly! The caterpillar has a special organ called the spinneret. It’s found in the head capsule. It gives out a unique liquid that turns into silk. (This is an amazing process, but I will save it bl”n for another time.) So, on some branch, or another isolated protected place, the caterpillar will secrete a lot of silk and make a silk pad out of it. It’s also called a hanging pad. Once its finished, it will turn around and the 2 back pro legs of the caterpillar will be at the silk pad. It sticks its back two prolegs into the pad with smooth hooks, and then, once it’s secured it lets go and it falls down head first, and it keeps itself in the shape of the letter “J”. The hooks are smooth and we will see why that’s important later on. It stays like this for about 12 hours, giving a movement here and there only once in a while. Then, in the 13th hour, it will do all types of calisthenics, sit ups, and lots of peristaltic movements as well. Then the real action starts. As the caterpillar is hanging upside down it starts to split open, from its head, “up” to its feet.
Here’s the caterpillar hanging upside down in a J shape.
![](https://shmuelwaldman.com/wp-content/uploads/2024/07/c1.png)
Then the skin starts to split.
![](https://shmuelwaldman.com/wp-content/uploads/2024/07/c2.png)
And more
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And more!
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At this point the shed skin is like a scarf around the caterpillar’s prolegs. This whole skin splitting process takes about 45 seconds! It happens through peristalsis. Then, in the next 15 seconds or so a very important part of the process takes place.
There’s a strange, special object, that show up out nowhere. It’s not a live organ. It’s just a small black stalk called the cremaster. You can see it in the picture here towards the top on the right side sticking out a little. It’s at the 2 o’clock position.
![](https://shmuelwaldman.com/wp-content/uploads/2024/07/c5.png)
It’s not known when exactly it is formed. At this point of the process the caterpillar lunges back and forth, and on one of its backwards lunges, all of a sudden, from below the “scarf” of skin, the cremaster slips out, coming from a hole in its body. (A hole that was never there before.) I have tried to get more information about it, but I couldn’t find anything.
In this picture you can see how the whole pupa is lunging backwards towards the left with the cremaster bending left, all the way at the top.
![](https://shmuelwaldman.com/wp-content/uploads/2024/07/c9.png)
What is it trying to do? It is trying to get itself plugged into the silk pad. This cremaster has a special microscopic Velcro type hooks which will stick tightly to the silk pad. Who made these special microscopic Velcro hooks? It’s an accident?! The accident knew that it needs to make these hooks?
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So, it lunges very aggressively, back and forth 3 to 4 times until the cremaster gets pushed in to the silk pad and then once it somehow “knows” that it has made a connection with the silk pad, it moves around some more in order to get itself stuck in very tight to the silk pad. This strong connection is vital since it enables the pupa to stay attached even in stormy windy weather. The next step is crucial. We want to get the loose skin off the caterpillar. We don’t want anything touching the pupa since it’s sensitive and fragile and it can injure the developing butterfly in its pupa. So, the caterpillar starts to wiggle and spin itself quite wildly. Its purpose is to detach the smooth hooks from the prolegs that were stuck into the silk pad, which is also keeping the loose skin from falling down. (The legs are not firmly held since the hooks are smooth and are easily dislodged from the pad.) When that happens, the entire loose skin finally falls to the ground. Mission accomplished! With that done, we are ready to discuss (next article) the wonderous, miraculous transformation that takes place, secretively while hiding in its pupa.
Here’s how the pupa looks a day later. Pretty cool, no?
![](https://shmuelwaldman.com/wp-content/uploads/2024/07/c10.png)
Let’s think about what just happened. How does the caterpillar “know” all the different moves that it must do for it to get successfully through all these steps? Where did the cremaster come from? It’s a bit of a mystery.
Rabbi Shmuel Waldman marvels at the wonders of Hashem’s creation, noting the miraculous aspects of this process. He promises future articles to explore the butterfly’s wings and migration, further revealing the intricate and wondrous design of nature.
Read the previous part of the article here.