Of the thousands of fly species in existence—including house flies and fruit flies—only a few are common in and around the home. They breed in animal waste, decaying food, or garden waste, picking up bacteria and viruses that cause human diseases. A few fly species even inflict a painful bite as they feed on the blood of people or their companion animals.
Most flies can develop from egg to larvae (maggots), to pupae, and finally, to adults in as little as one week; however, development typically takes three weeks. House fly adults typically live about two and a half weeks during the summer, but they can survive up to three months at lower temperatures. Some even winter indoors.
- Eggs and larvae: After a day or two, eggs hatch into maggots and feed on the material onto which the adults laid eggs. Maggots look like tiny worms—they lack definite heads, eyes, antennae, and legs.
- Pupae: Following three periods of growth and molting, the maggots stop feeding, burrow into drier areas, and pupate. The pupa is an oval brown covering in which the larva changes into an adult.
- Adults: Adults mate one to two days after emerging, and females lay 100 to 150 eggs on garbage or other decaying organic material several times during their lives.
Because flies secrete saliva and waste wherever they rest, they are excellent transmitters of disease. Authorities believe that house flies spread more than 65 human bacterial and viral diseases, including diarrhea, cholera, food poisoning, and dysentery. In addition, their persistent feeding on moist secretions, such as those around the eyes, causes physical and emotional discomfort to both people and their pets.
To reduce the number of flies to an acceptable level, use a mixture of controls. Limit their food sources so that they cannot breed in large numbers: Keep trashcans clean and tightly covered, and promptly pick up and dispose of pet waste from your yard. Also, restrict flies’ entry to your home by using tight-fitting window and door screens. Caulk openings around your home’s pipes and electrical conduits.
When flies invade your home, consider using a home spray for spot treatments. Yard sprays can also be used as an outdoor barrier treatment. Apply the spray to areas where flies rest before entering the house, such as walls in a garage, on porches, and around doors and windows. To interrupt an out-of-control fly infestation indoors, consider using a fogger.