Day 1 (03.02.2021): 1st Observation
I have taken this caterpillar and will try to feed it until it becomes a moth while recording its progress and different stages.
The leaves on the area I found it were mainly Oxalis pes-caprae, but I will also add different kinds of leaves in its enclosure, as well as some soil.
Up until now it has eaten from the Oxalis leaves.

Day 2 (04.02.2021):
Today, and yesterday night, I noticed some bite marks on the Oxalis leaves. I was away most of the day, but the caterpillar was inactive the time I arrived. Not wanting to risk it having a narrow diet, I added a Lantana leaf, some fresh Oxalis leaves with some flowers, and a Prasium majus leaf. These are present in the area.
Tomorrow I will check which have been bitten.

Day 3 (05.02.2021):
As far as I could see, it didn't eat any of the leaves. What I noticed though, is that it started nibbling on the stalk of an Oxalis flower.
I brought it a Malva leaf, a fresh Oxalis leaf and an Oxalis flower. It got straight to work eating the pollen and then it stayed inside the flower resting (I guess).
It stayed in there for the rest of the day.

Day 4 (06.02.2021):
Today I noticed it is still inside the Oxalis flower, having eaten all the anthers of the stamens.
I brought 2 fresh Oxalis flowers and a leaf. It didn't want to grab onto the leaf, but it grabbed the flower. Again, it spent the whole day inside it, eating when needed, while acting completely disinterested to its surrounding foliage.
Before going to sleep I noticed some silk threads over the flower. Not many though.
I don't think I can leave it inside the flower tomorrow though, as the petals wither away.

Day 5 (07.02.2021): 2nd Observation
Not much changed today, it is still inside the flower and the silk threads are still there.
I made an observation of this, where you can see it residing in the flower and the silk threads in the entrance of the flower.
Let's see if anything happens tomorrow.

Day 6 (08.02.2021):
Today the caterpillar moved from one flower, which had withered away, to the fresher one.
In the evening, I noticed it had ripped the stamens and the caterpillar was hiding between the flowers.
It was doing something with its mouth, I guess producing silk or something like that, and then retreating back to the space between the flowers.

Day 7 (09.02.2021): 3rd Observation
Today I offered 2 more Oxalis flowers, plus a leaf, and took some pictures of the caterpillar's body. The markings have became more distinct, and my suspicion is that it might be a Gymnoscelis rufifasciata larva. I guess we will see in the next days.

Day 10 (12.02.2021):
Today the caterpillar was acting a little bit weird. I found it on the ceiling of its enclosure (which is a mask). I added the daily flowers and leaf, but it didn't seem interested this time.
Normally it goes straight to the pollen, this time it went around, like not knowing where to go.
Eventually it entered the flower again.

Day 11 (13.02.2021): 4th Observation
The caterpillar didn't move much this morning.
When I changed the flowers, it was barely moving. Its mouth had some silk stuck to it and the flower, but other than that, not much else.
Later today it, unfortunately, died...