The first time a person may encounter maggots is in spoiled meat. But maggots actually are in more places than many people are aware of. Maggots are the larval state of flies. They are used beneficially in medicine to remove necrotic tissue. But they are primarily known as nuisance pests in garbage or because they have attacked roots of garden plants. Maggots may invade a home in a number of ways.
Many modern homes do not experience large-scale infestation of flies. Homes with central air systems are typically kept tightly-sealed to prevent conditioned air from escaping in summer. Because of this, flies do not often find their way into homes. Homes where a window is left open to cool the air are more likely to have an infestation. If flies are allowed into a home unhindered, they can lay eggs that will hatch into maggots. House flies, which are the most common source of infestation, are typically attracted to man-made food. These types of flies are usually found near garbage, animal wastes or discarded fruits and vegetables.
Flies such as blowflies are less common than house flies because they are attracted to carrion, which is not typically found in a home. Blowflies or other carrion-feeding flies may find their way into a home in search of dead mice or squirrels that have become trapped in the walls, cellars or attics. Blow flies may also be found in pets' fecal material. Blow fly maggots also are found in homes that contain pet hoarders or in homes where animal waste hasn't been cleaned up.
Some flies, such as cluster flies, are common in homes during cool months. These flies may gather in the south-facing portions of a home. These rooms are usually heated to the warmest point by the sun in winter. During winter, flies such as the common house fly breed most actively. Because of this you are more likely to see maggots of this variety during winter. During summer, blow flies may seek out the presence of a home for relief from the outdoor heat.
The organic content in potting soil is often a draw for flies such as the fungus gnat. These pests find their way into a home as plants that have been left outdoors in summer are brought in for the winter. Fungus gnats and other flies can be found on the surface of potting soil containers. Overwatering these containers can increase the populations of fungus gnats as their food of choice, potting soil fungus, also increases.