My Emperor Moth Caterpillars: The Story So Far

Holding an Emperor Moth during my bug hunt in 2017

Today is the 4th anniversary of this blog. Can you believe it? Four years already! To celebrate, I thought it would be great to look back at one of my highlights of this year: my emperor moth caterpillars. Last year, as part of my big bug hunt quest (in which I went in search of a selection of invertebrates that I tasked myself into finding across Norfolk and Suffolk), I wanted to also raise some moth eggs that I had found on a wall outside my flat. Unfortunately, I was unsuccessful in hatching them. So this year, as part of a late birthday present, my parents bought me some emperor moth eggs from a breeder for me to try again. Here's a run down of what happened up until now...





My late present - 30 Emperor Moth eggs

On the morning of May 19th, while watching the Royal wedding, the special delivery arrived. Thirty tiny precious brown eggs encased within a small plastic tube. They were laid 4-5 days prior before being sent in the mail to me. I was fairly excited as I waited for them to hatch.

Newly hatched

The wait wasn't long at all as they all hatched the next night on the 20th! I was so unprepared that I had to get Mum to deliver some bramble leaves from her garden at 10pm that night. They were so tiny, about 2mm in length and jet black. At this stage, they were pretty easy to look after as I kept them in a small tub with a few leaves inside.







Clustering together for their first skin change

Then, between the 25th and 26th of May, something strange was happening. They all started to cluster together and appeared lifeless. They were going through their first skin change. It had me worried that first time as I thought I did something wrong and killed them all. Thankfully, a day later they emerged out of their old skins looking slightly bigger and hairier than they were before.




What they looked like after their first skin change

Skin change number 2

Their second skin change happened just two to three days later. It was very similar to their previous skin change, just even more hairy and a few centimetres larger. This was when they began to be more lively. They were starting to move around a lot, exploring the slightly larger box that I moved them into and their appetite was becoming quite demanding.

Skin change number 3

When the third skin change occurred, they were becoming noticeably orange. I was pretty lucky to watch one in the process of shedding out of its old skin, emerging as this bright green and spotty creature. As they were getting too big for a simple lunch box, it was time to move them into something bigger. I bought a large plastic bucket with a lid, which my dad drilled air holes into, and I collected bramble branches full of leaves and placed them into a jam jar full of water.  

The fourth and final skin change

By the fourth skin change (June 9th), it was becoming more and more of a chore that was starting to annoy me. The bigger they got, the more frass (caterpillar poop) they produced, which also got bigger as they grew. I was also getting sick of collecting new bramble branches and replacing them with the older ones every day. It was still rewarding though. They were now 4cm long and this was to be their last skin change and they were doing it at different times, taking several days between when the first finished shedding and when the last individual did the same.








Constructing a cocoon

They were in this final skin for more than a week. During the 17th and 20th of June, I was on holiday spending a few days in London with my parents. I handed my caterpillars to my friend David to look after them while I was away. I don't think he knew what I was getting him into as it was at this time that the little devils decided to pupate. David was pretty worried and unsure of what to do. So I told him to fill the bucket with egg cartons and to place leaves on top for those that weren't ready to pupate just yet. When I got home from my holiday, I relieved David from the stress of pupating caterpillars. There were still plenty yet to build their cocoons and I was lucky to watch some of them construct these silken structures. Slowly, their green bodies were disappearing behind a cover of brown silk. It took two weeks until the final caterpillar pupated on June 28th. I was free from the daily chores of being pricked and scratched by bramble branches and removing an endless supply of frass.

A completed cocoon

What my moths will look like when they emerge next year

 So what happened since then? Well, during the summer and autumn I was advised to spray them water once every few days to keep them from drying out. I hope I've done a good job as it was extremely hot this summer and I didn't realise that was what I was suppose to do until a couple days after the final caterpillar pupated (two weeks since the first one!). If their wild cousins can adapt and develop in such extreme conditions, surely mine will do the same, right? Now that it is winter, I have since sent them to my dad's shed, where I'm hoping he still remembers to continue to spray them. Hopefully, when spring arrives once more, I will have some survivors that will complete their life cycle and emerge as moths like the ones I saw in 2017 at Weeting Heath. Fingers crossed!