dimespin:

The giant bees have two languages. One is a sign language very similar to human sign languages, but with more hands, fewer fingers, and a hard-coded method of communicating distance (it’s basically exactly like the bee dance language, just done with the hands)

The other is a tactile language. This one is communicated using light touches with the antennae, similar to morse code with a few more components than dots and dashes. They use this tactile language to communicate with grubs, giving them their first taste of language by associating certain words with the experiences they can perceive, like being held or fed. This also becomes the grub’s first opportunity to understand its own body as nurse bees inform it what it may be feeling.

When adult bees emerge from the comb after pupating, they have near-complete adult faculties but cannot speak the full sign language, since obviously, they have never seen it and didn’t have hands before to speak it with. So for a couple years after emergence they rely on the tactile language, allowing them to function in a rudimentary way while they get a crash course in a full and complex language.

Being a grub, and being a new adult worker are both vulnerable times where they rely a lot on trust and care from their sisters, so the bees associate the tactile language with this vulnerability. Even in older bees it is the language of trust, care and closeness, they never stop using it.