[Valpal1]

Sounds like someone planted those. Probably an angry vegan...

Or an employee that's tired of working and wants to go back on unemployment.

I've raised maggots (for aquarium fish food). They are unlikely to crawl up from the floor drain to the meat case. A dead rodent lodged up in the case somewhere is a more likely scenario. Also they should look up. We once had a mouse expire above a ceiling tile, the kind with multiple perforations and the smell was going up and the maggots were dropping down onto my mother's bed.

[vetvetdoug]

Excellent hypothesis as when I was a sanitation inspector I noted that very few inspectors and employees ever looked up to see a source of food contamination. Nobody ever looks up.