Aelian, On the Nature of Animals 1.24
“The male viper has sex with the female after he wraps himself around her. She tolerates her husband and doesn’t feel one bit of grief about it. But when they are at the end of their sexual activity, the bride repays her mate with devious affection for this intercourse: for, as she lays astride his neck, she bites it off with his head.
So, while he dies from sex, she gets pregnant. But instead of bearing eggs, she has live offspring and they immediately exhibit the worst part of their nature. They eventually eat through their mother’s womb and emerge, avenging the death of their father. What, oh dear tragedians, are your Oresteses and Alkmaiones in comparison to this?”
24. Ὁ ἔχις περιπλακεὶς τῇ θηλείᾳ μίγνυται· ἡ δὲ ἀνέχεται τοῦ νυμφίου καὶ λυπεῖ οὐδὲ ἕν. ὅταν δὲ πρὸς τῷ τέλει τῶν ἀφροδισίων ὦσι, πονηρὰν ὑπὲρ τῆς ὁμιλίας τὴν φιλοφροσύνην ἐκτίνει ἡ νύμφη τῷ γαμέτῃ· ἐμφῦσα γὰρ αὐτοῦ τῷ τραχήλῳ, διακόπτει αὐτὸν αὐτῇ κεφαλῇ· καὶ ὁ μὲν τέθνηκεν, ἡ δὲ ἔγκαρπον ἔχει τὴν μίξιν καὶ κύει. τίκτει δὲ οὐκ ᾠά, ἀλλὰ βρέφη, καὶ ἔστιν ἐνεργὰ ἤδη <κατὰ>τὴν αὑτῶν φύσιν τὴν κακίστην. διεσθίει γοῦν τὴν μητρῴαν νηδύν, καὶ πρόεισι πάραυτατιμωροῦντα τῷ πατρί. τί οὖν οἱ Ὀρέσται καὶ οἱ Ἀλκμαίωνες πρὸς ταῦτα, ὦ τραγῳδοὶ φίλοι;