What do you do if you found a maggot in your childs baby food?

Reassurance. I concur with dr. Proffitt, but would like to reassure you that although disgusting, the maggot is unlikely to cause your child harm. The spoiling food, which supported the maggot, is more likely to be the problem-which would probably present with vomiting and diarrhea.
Many things. I would observe the baby closely for illness especially vomiting and diarrhea and fever. I would check all sources of known baby food and discard and if this were an unopened container of food, i would notify the manufacturer of the name, lable, lot number and expiration date. You may wish to notify the store where purchased and the loocal health department. See your pcp if concerned.