"Maggot" is a general term for the larvae of dipteran flies, including species such as common houseflies, blowflies, apple flies, blue bottles and many others. These flies are characterized by their antennae and small bodies, so most maggots look the same, regardless of their species.
Housefly, or Musca domestica, maggots are the kind most commonly seen in homes. During the summer, houseflies look for suitable places, such as rotten food and fecal matter, to lay their eggs. These eggs can take up to 24 hours to hatch. The maggots that hatch from them look like small cream or pale yellow grains of rice. Bluebottles, another species of maggot commonly found in homes, tend to be slightly longer than common housefly maggots but have a similar appearance otherwise.
The maggots of apple or railroad flies are considered a pest species, as these flies ruin apple crops by laying their eggs directly into the apples. Maggots are typically tubular with no discernible body parts. The rat-tailed maggot, however, is an aquatic maggot that usually lives in toilets and has a long tail that is used as a breathing tube. Some maggots can also be used medicinally, as certain species, such as the bluebottle larvae, eat away at dead, rotting flesh and promote healing.