She contacted Progressive Enterprises, which owns Countdown, but received "a very vague response".
She then contacted Tegel, which expressed serious concern and offered her an apology and two $15 Tegel vouchers. The company's head of quality control told her the creatures appeared to be mealworms not maggots, but this could not be confirmed.
She had not had any adverse health effects, other than feeling "traumatised".
Countdown and Tegel representatives said they were investigating.