Cecropia Moth Project, 5 Months Later

Cecropia pupa

On October 26th we removed the cocoons from the refrigerator after exactly five months of winter simulation. The outer cocoons were very brittle, paper-like, and dry (you may recall they are made from leaves bound with silk). We read that it is OK to remove the outer and inner cocoons to get a look at the pupa, and naturally we were curious. After some research about the proper way to do this we got to work. 

One of the cocoons (outer)

Using a pair of fly-tying scissors, we trimmed back the outer cocoon. This part is relatively easy since the skin of the outer cocoon is so dry and brittle. It is important to keep the scissors as close to the surface of the cocoon as possible. If the pupa is punctured it could result in death. 

Here and below: The outer cocoon and inner cocoon

Next, the scissors were taken to the inner cocoon, which is covered in a layer of silk that feels like thin, dry hair. The cocoon itself is brittle but thicker than the outer cocoon. Cutting through the inner cocoon feels much like cutting a thick piece of construction paper. Again, it is crucial that this is done slowly and with great care. The scissors should stay close to the surface of the cocoon so as to not puncture the pupa. 

We felt movement almost immediately after beginning to cut the inner cocoon. The pupa shook and vibrated inside. Pretty wild. We proceeded slowly. Eventually we created a big enough opening to see inside, and there he was, writhing and wriggling. 

Inner cocoon cut open to reveal pupa

This particular pupa is a male, which we determined after seeing the large antennae. 

Pupa, antennae view

Pupa, rear view

Below is a video of the pupa in motion. 

After our success cutting open the first cocoon we decided to remove the outer cocoons from the three others so that everyone is on the same page. By doing this we also hoped to determine if the others are alive - and they are! After some harmless poking we felt movement from each inner cocoon.

We placed the four cocoons back in the aquarium where they started as wee black caterpillars. The aquarium is lined with brown paper and sticks are taped to the sides. When the moths emerge, they will climb up the sticks and hang vertically. We expect this will happen in the next week or two, so stay tuned.

Cecropia Moth Project, Day 99

The six weeks are up and it is time for the cocoons to go into the refrigerator for the winter simulation. After five months we will remove the cocoons from the refrigerator and wait for the moths to emerge. Take care until then.

The cocoons in a freezer bag, labeled with the date.

Cecropia Moth Project, Day 55

Cecropia caterpillar cocoon

All four caterpillars have pupated and they are now silking away inside the cocoons (we can hear them working). The cocoons are very hard and the caterpillars will continue to add more layers of silk over the next six weeks. After this six weeks of work we will place the cocoons in the refrigerator to simulate winter for five months.

Cecropia caterpillars cocoons tied to a string

Cecropia Moth Project, Day 51

This past week we started to get worried that something was awry in caterpillar world.  After looking again at the other Cecropia blogs that we've been referencing throughout this process we realized that our caterpillars had long passed the five week mark when they should have started spinning cocoons. Our caterpillars were nearing seven weeks, and we noted that they'd become less active and that their frass size and output had decreased. Our immediate concern was that we'd given them a disease by touching them (you are not supposed to touch the caterpillars without first thoroughly washing your hands, as bacteria is transferred easily to the insects). While we'd generally taken precautions there had also been times when we hadn't.

Our concerns were quickly laid to rest when we returned home yesterday afternoon to find that one of the caterpillars had taken a giant frass, expelling a large amount of water in the process. We'd read that this is what happens before they are getting ready to pupate, as they will be locked away for months unable to empty their bowels. Interesting to note is that the caterpillar was hanging completely vertical from a twig, holding on with only its front (real) legs -- the first time we'd ever seen this behavior. The front legs do not have grippers like the prolegs, so it seemed odd that the caterpillar would be dangling in this way that to us looked rather precarious.

Holy frass!

Red arrows point to front legs, blue arrows point to prolegs

Within an hour the caterpillar had gripped back on entirely and moved to a different location in the habitat. Later last night we found that the caterpillar had started spinning (!) and pulling leaves in around it (we padded the habitat with additional leaves knowing that the caterpillars piece the cocoon together by pulling in leaves). This morning we woke to find a tidy looking albeit half finished cocoon. Exciting.

We imagine that we'll be seeing more frassy messes and cocooning in the next day or so. 

First cocoon

First cocoon, another angle

Cecropia Moth Project, Day 47

5th instar Cecropia caterpillar

The Cecropia caterpillars continue to grow, and they'll likely start spinning cocoons any day now. We are still waiting for the front horns to turn orange as we've seen on other 5th instar Cecropia caterpillars. Perhaps this won't happen. If it doesn't, we'll be curious to know why. Maybe diet?

New habitat arrangement

We changed the habitat once again to accomodate the caterpillars' desire to hang and their eventual need to spin. We drilled holes into a small wooden board and placed the water tubes and additional sticks within those holes. We are keeping the habitat flush with maple leaves. If caterpillars had emotions, I imagine they'd be happy with the new arrangement. They are quite active and eating a lot.

Cecropia Moth Project, Day 39

No real updates to share other than a dramatic episode from last night. A bit of a traffic jam occurred atop one of the leaf stems, and this resulted in some unfriendly poking, prodding, and theatrical writhing by the caterpillars. Ultimately the jam was cleared up, but not without these initial fisticuffs.

Cecropia Moth Project, Day 36

5th instar Cecropia caterpillar 

As we suspected, the caterpillars molted again! We're a little confused about what this means. Are they still in the 5th instar stage? Do they change twice in the 5th instar stage? We need to do some research.

Unlike with previous molts, the caterpillars' appearance was nearly unchanged after this molt. However we did note more pronounced black spots on the tail horns and an angling of the back horns. The suctions on the feet are also much larger.

Bottom caterpillar is mid-molt. You can see that the yellow spikes don't have black rings or spots yet. These develop over a few hours.

I was able to capture video of the last parts of the molt, during which the caterpillars shed their skin.