Herodotus wrote about gold-digging ants in India which were smaller than dogs but larger than foxes.
[1] Aelian wrote: "The Indian ants (μύρμηκες οἱ Ἰνδικοὶ) which guard the gold will not cross the river Campylinus.
"[2] The Myrmekes appeared in the Percy Jackson & the Olympians book The Demigod Files, where they were seen in the story "The Bronze Dragon."
They end up capturing Charlie Beckendorf when he tries to retrieve a Bronze Dragon head that they have found.
Later, when the two met the Palikoi (geyser gods), one of them, Pete, shined a spotlight and attracted the attention of three Myrmekes.