The lifecyle of the common house fly, Musca domestica, resembles that of most flies. Flies begin life as eggs, which go through larval and pupal stages before reaching adulthood. The reproductive cycle of a house fly depends on environmental conditions such as temperature – the warmer the temperature, the shorter the cycle. The shorter reproductive cycle allows for 10 to 12 generations in a single year. Depending on environmental conditions, the house fly may complete all stages of life in as little as 6 to 10 days. However, the average length of time to develop through all life stages generally falls between 35 and 55 days.

House fly eggs normally hatch within a day into tiny, whitish larvae commonly referred to as maggots. Warmer weather, especially found in subtropical and tropical regions, may decrease egg hatching to less than 12 hours. In the temperate and arctic regions found in Canada, house fly eggs typically hatch in no more than 24 hours; however, eggs laid indoors where temperatures are controlled frequently hatch more quickly. First instar larvae are about 5 1/2mm in length. Mature larvae may measure as long as 7 to 12mm. The larvae undergo three instars, or periods between molting and sexual maturation, during which the larva sheds skin prior to reaching the pupal stage. House flies spend about two weeks going through larval stages throughout most regions in Canada.

The small, wormlike maggots eventually enter into the pupal stage, which feature hard encasements ranging from brownish or deep red in colour to dark yellows and even black. House fly pupae are oval in appearance with rounded ends. Inside the pupal casings, the pupae mature into adults. The process of development from pupal stages into adulthood often takes a couple of days to four weeks in temperate climates. In many climates found throughout Canada, house fly pupae may need as much as three to four weeks to fully develop into adults.

Factors Affecting House Fly Lifespan

Environment

Several factors influence the lifespan of house flies. Of the contributing factors, environment plays an important role in determining the lifespan house flies enjoy. House flies flourish in areas of warm temperatures and humid air. Tropical and subtropical regions represent the most ideal climates for house flies to live. In warmer climates, fly development times shorten along with average lifespan. A fly may live only a week as an adult in warmer, tropical or subtropical regions. Quicker life cycles account for greater populations over time. Conversely, cooler continental, subarctic, and polar/alpine climates predominant throughout Canada greatly elongate overall fly lifespan, primarily due to slower metabolic rates, especially during colder seasons. During warmer months, Canadian house flies typically become more active and have a somewhat shorter lifespan.

Diet

Adequate access to food sources also affects fly lifespan. House flies tend to live in close proximity to humans and other animals. Garbage, faeces, and remains of organic materials serve as main meal sources for house flies. Warmer climates often support more fly-friendly breeding grounds, as flies breed more in warmer temperatures. According to a recent National Geographic article published October 2010, close proximity to food may, in fact, reduce the lifespan. The article summarizes a study which examined the diets of house flies in correlation with overall length of life. A typical house fly with adequate access to food lives around 45 days; however, flies more removed from food sources and unable to smell foods — the fly’s main means of locating sustenance — lived roughly 10 days longer. The flies able to eat freely, as those representative of house flies living in warmer climates close to open food sources, lived roughly 10 days fewer than the average fly.

Season

Seasons also affect the average lifespan of house flies. The flies are most active during the warmer summer months. During winter, flies primarily hibernate. Warmer temperatures promote more widespread access to food sources, as well, which accelerates fly metabolic rates and reduces life expectancy. Hibernation often elongates the lifespan, as the insect’s metabolism slows down while overwintering. Canadian climates generally promote longer fly life, due to consistently cooler temperatures which feature less access to food sources.