They can crawl on walls but are most often observed crawling on a floor to a dry area to change into their next form.
Life Cycle
Adult flies seek out rotting garbage, manure or dead animals to lay eggs on. They are laid in batches, and several flies can add to the collection, making for a large number of maggots. They hatch in eight to 20 days, depending on conditions -- the more moist a decaying environment is, the sooner they hatch. Once mature, maggots crawl to a dry spot and pupate, which lasts for one to three weeks. Adults emerge from the pupa, fully grown, and are ready to lay eggs of their own within a few days.
Identification
Maggots have the appearance of a squirming piece of rice. They are often present with dozens of their siblings on or around garbage, rotting meat, feces or a dead animal. Cream colored and almost greasy in appearance, maggots have pointed mouth parts visible on the tapered end. Mature maggots can be anywhere from 1/4 inch in length to 1/2 inch. Maggots can be found on the rotting vegetation or animal or can be seen traveling to a drier location to pupate.
Mobility
In their quest to find a dry spot to pupate, maggots can venture 50 feet or more away from their food source. They are often spotted crawling across a floor, the ground, on garbage cans or even walls. They will be more prone to crawling on a wall if a garbage can is next to it.
Cleanup
If you discover maggots moving in your home, seek out the offending material as soon as you can to remove it and prevent further maggot infestation. Dispose of the garbage or dead animal in a securely tied plastic bag and thoroughly clean the area with a bleach solution comprised of a 2 tbsp. of bleach mixed with 1 gallon of water.