Flies are often metallic in appearance, with feathery hairs on the terminal antennal segments of the males. Adult flies have sponge-like mouth parts, while maggots have hook-like mouth parts.
Common house flies are attracted to decaying organic filth such as feces and rotting meat, whereas fruit flies seek sugary substances and feed more commonly on overripe fruit, spilled soda and alcohol. Drain flies require moist climates and organic materials and will be attracted to drains where they will lay their eggs.
A pest control professional should be contacted for assistance.