Araneae needs her latex shined. And the sub has turned up without shine. While there's a little bit confusion over who should have brought the shine (in Araneae's dress and the sub's nudity it's not like either have pockets)

So, starting with her arm, he can shine the latex with his tongue.
He is under strict instructions not to miss an inch.

Running his tongue up the arms, the sides... this does mean he needs to get in close. The crotch, her breasts, her armpits...

At least by the time he is complete the shine is adequate.