What Causes Maggots in a Home?

Maggots -- the larvae of various fly species -- can show up in odd places in your home when the adult, egg-laying females find a welcomed spot to lay their eggs. Some flies lay eggs on overly moist houseplant soils, while others prefer to reproduce on decaying organic materials. You must find and eliminate fly breeding sites in order to control maggots.

Moist Soils

Moist potting soils full of decaying organic materials frequently draw fungus gnats (Mycetophilidae spp. and Sciaridae spp.) and occasionally attract phorid flies (Phoridae spp.). Adult females lay eggs on the damp plant soil and the hatched larvae feed on decomposing plant material and fungi.

Make your potting soils less attractive to egg-laying flies by:

• allowing the surface of the soil to completely dry between irrigation sessions
  
• throwing out dead plant parts to keep the soil clean or
  
• draining water from the saucers beneath pots.
  

Spraying a houseplant-safe aerosol insecticide containing pyrethrin or resmethrin over the soil's surface and around the pot edges can kill flies before they have a chance to lay eggs. Spray every two or three days for 21 to 28 days to get rid of the adult flies. (ref 1)

Decaying Organic Matter

Decaying organic matter attracts various fly species, including houseflies (Musca domestica), the most common source of household maggots, fruit flies (Drosophila spp.), phorid flies and picture-winged flies (Ceroxys latiusculus).

Female flies lay eggs in decaying organic matter, such as animal waste and rotting fruits and vegetables. The flies also reproduce on the little bits of decaying materials found in dirty garbage cans and recycling bins. The eggs hatch into maggots, which require wet or semi-liquid media to feed upon and keep their bodies moist.

You can reduce the risk of maggots showing up in your home by taking the following actions:

• don't leave any food-- including pet food-- uncovered inside of your home or garage
  
• clean litter boxes daily 
  
• rinse items before chucking them in the recycling bin
  
• throw out decaying fruits and veggies
  
• use plastic liners inside of household wastebaskets.
  
• empty wastebaskets daily, throwing contents into an outdoor trashcan and
  
• spray emptied recycling bins and garbage cans with scented disinfectant.

Rotting Meat

Other flies are less common in houses because they feed upon and reproduce on rotting meat. Those flies include blowflies (Calliphoridae spp.) and flesh flies (Sarcophagidae spp.), both scavengers that lay eggs on freshly dead animals or in garbage containing meat scraps.

The adult females pick rotting meat for egg-laying sites because it offers an abundant food source for the larvae. Once hatched, the maggots use their mouth hooks to scrape up the rotting meat and their bodies secrete enzymes that help putrefy the flesh, both of which help create the semi-liquid environment the larvae need to survive.

Blowflies and flesh flies don't typically make their way indoors, but they are tiny enough to slip through the cracks around windows or doors if they smell rotting meat. Prevent rotting meat-eating flies from producing maggots in your house by:

• inspecting screens for damage and fixing any tears immediately
  
• installing weatherstripping around doors and windows
  
• placing kick-plates under doors and
  
• caulking the small gaps around doors, windows and vents leading into your home.