Another proverb from the Suda:
“An old’s man head is a raisin: this is a metonym from the fact that their whole body is weak. It is used for people who are no longer useful. There is also the proverb “an old man’s jaws are stiff”—this is used for people who eat a lot when they are old. Also, “don’t look at an old man’s ass”, which is used for people who are no longer useful in the same things. There is also: “When a man is doing badly, his friends are away”—this is applied to those who find no help in hard time from their friends.”
Ἀνδρὸς γέροντος ἀσταφὶς τὸ κρανίον: ἀπὸ μέρους. ἐπὶ τῶν μηδαμοῦ χρησιμευόντων, παρόσον ὅλον τὸ σῶμα ἀσθενές. καὶ, Ἀνδρὸς γέροντος αἱ γνάθοι βακτηρίαι, ἐπὶ τῶν πρὸς τὸ γῆρας πολλὰ ἐσθιόντων. καὶ, Ἀνδρὸς γέροντος μήποτ’ ἐς πυγὴν ὁρᾶν, ἐπὶ τῶν πρὸς ἔνια μὴ χρησίμων. καὶ, Ἀνδρὸς κακῶς πράσσοντος ἐκποδὼν φίλοι, ἐπὶ τῶν ἐν τοῖς κακοῖς μηδεμίαν εὑρισκόντων παρὰ τῶν φίλων ὠφέλειαν.