UncaringDoodles

For context: the white witch is one of the contenders for the largest moth in the world (biggest *wingspan*--loses to the atlas in terms of wing surface area, and loses to the regal for weight). It has a huge range, and the adult is fairly common.

The observation of this caterpillar above was made in Panama, January 29th 2025, but posted during March, and posted on iNaturalist by Andrew Quitmeyer. On the same date and in the same spot, there was also an observation posted by Hubert Szczygieł. I am assuming both original posters were together when they made this observation.

Looking further into it, I noticed that there were a few earlier observations, but perhaps this is the first scientifically confirmed one. I thought I might just mention it.

I found an observation posted by Lia Nahomi Kajiki in November 2022 in Brazil. Additionally, I found an observation from September 2018, which was posted by Hervebreton during July 2024 in French Guiana.

White Witch Caterpillar Posted by Lia Nahomi Kajiki, Nov. 28, 2022 (iNaturalist).

The OP told me that as far as they know, the caterpillar in the picture is the first larva they have been able to get to adulthood, thus proving its ID. It is likely, that the finders of other observations were pretty confident in them being a white witch caterpillar, as there are not many erebids (members of the family of moths called Erebidae) that get quite that big. Regardless, we have a 100% confirmation now.