for something to become full of ants, swell with ants (see Molina)
Alonso de Molina:
azcayoa. n. (pret. onazcayoac.) henchirse de hormigas. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 10r. col. 2. Thanks to Joe Campbell for providing the transcription.