Some were carrying the white whatever-it-is down the trunk and through the casing, while one ant carried the . . . (are they larvae?) up the trunk. Unfortunately, I also saw a small black wasp enter the cavity near the ground/base of the tree. I am unsure whether the fifth photo is an unrelated moth/butterfly cocoon? It was situated in an alcove at the base of the tree where the ants were busy entering and leaving
Thanks for the pics Lisa. The things going down look to be worker larvae and the ones going up look like very advanced queen larvae, nearly pupae (they don’t have pupal cases, unlike a lot of other ants). They move brood around a lot, giving them more or less warmth or space depending on how quickly they want the brood to mature. The wasp could certainly be parasitic but not sure about the cocoon. Cheers, Jon
Thank you so much for interpreting the photos, and sharing your knowledge - fascinating! The things you learn when you stop and look for a little while . . .