The Lifespan of a Fly
Unless you are literally living under a rock or in Antarctica, you would be familiar with the insects called flies. The most uninvited and stubborn guest in your house that refuses to leave.
They carry around 100 disease-causing germs and transmit diseases through their feet and mouth. Flies will contaminate anything they touch, and they touch almost everything around.
How Long Do Flies Live?
The lifespan of a fly depends on their species. There are almost 16,000 different species of flies each having their unique characteristics and lifespan ranging from days to years. Generally, the lifespan of flies is around 15 – 30 days, but several other factors contribute to their life expectancies like temperature and living conditions.
Temperature is the major factor considering flies live in warmer conditions. There are only few fly species which can survive colder temperature. The optimal survival temperature for houseflies is from 62 – 90 degrees Fahrenheit. An adult housefly and fruit fly can live up to 30 days in warmer temperatures at 75 – 80 degrees Fahrenheit.
Flies which live in warmer conditions like those of houses or laboratories have a larger lifespan as compared to their counterparts living in wild.
What are the Stages of the Life Cycle of a Fly?
Whether its housefly, fruit fly or any other species of fly, one thing which is common among all is that they all have to go through a four-stage life cycle.
- Egg
- Larva
- Pupa
- Adult
Every fly must go through these stages of life, but the time each fly spends on one stage varies with the species, temperature, and the surrounding conditions.
The life cycle of a fly begins with the egg which hatches into larva within 24 hours. The larva can take several days to several weeks to develop into pupa as temperature and food availability plays a major role in it. Development of a pupa into an adult fly also relies on the surrounding conditions and temperature and a pupa can take days to weeks to become an adult fly.
The ideal temperature for a larva to grow quickly is 95 degrees Fahrenheit and will take up to 13 days to reach the pupal stage. The pupa will reach the adulthood in few days if the temperature remains 90 degrees or more, but if the temperature is around 60 degrees, it will take up to 4 weeks to reach the adulthood. Life as an adult fly can be anywhere between 15 days to 2 months. This all depends on ideal temperature and food (especially sugar) availability.
The Egg Stage
The life cycle of a fly begins with eggs. The size of a single fly egg is 1.2 mm and is almost impossible to locate. Even when in clusters (as eggs are laid in groups) they are hard to locate and are easily overlooked.
It all starts with a fertilized female fly finding an appropriate place to lay eggs. Once she locates the ideal place, she lays eggs there. An ideal egg-laying place for flies is somewhere providing damp surroundings to eggs as they won’t hatch if dried, the place should also contain food for the larvae on which it will feed upon after hatching from eggs. Their egg place could be bin, trash, feces or any other decomposing organic material which will feed larvae upon hatching.
Usually, several flies lay eggs in close proximity hence producing a large population of larvae simultaneously.
How many eggs are laid at once?
Flies multiply quickly in a shorter time because of their brief life cycle. A pair of flies with their offspring can produce up to 1,000,000 offspring in just a couple of weeks.
A single fertilized female fly can lay around 500 eggs in her lifespan. She lays eggs in groups of around 150 at a time and these unnoticeable eggs will produce larvae in a couple of days. Later if the conditions favor they will complete other stages of life and you will be surrounded by hundreds of adult flies.
The Larvae Stage
If the surrounding conditions are suitable, a fertilized egg hatches within 8 – 24 hours. Larvae upon hatching feed on the organic material around such as trash or feces. A fly in its larvae stage feeds for several days & weeks because it is storing protein and nutrients for the upcoming pupa stage.
High moisture animal dung is ideal for larvae to feed upon and since it is nutrient rich. It provides an excellent developmental substrate for larvae.
A larva’s length ranges from 3 mm to 9 mm, these fly maggots are a creamy white color. They have a legless cylindrical frame which tapers around their head and they continuously wriggle around. The fly larva does not have a face but only a mouth for consuming decaying food and proteins.
The ideal temperature for larval development is 95-100 degrees Fahrenheit and it takes 4 – 13 days to complete its development.
The Pupae Stage
Once they are completely developed and have taken enough food, larvae leave their food source and search for a dry and dark place to pupate. It can crawl up to 50 feet to find the ideal place for the pupal stage. In the pupal stage, the legless larvae grow six legs, pair of wings, compound eyes and turn into a complete adult.
The average size of pupae is 8mm and unlike larva, they are rounded in shape. Pupae gradually change its color from the previous stage. First, it develops a yellowish hue, then turns into red and brown and finally, due to aging, develops the black color of the fly.
In the favorable climatic conditions, a pupa completes its development in 3 – 6 days, whereas if the optimal temperature is not available the pupal stage can last up to 27 days.
The Adult Stage
After completing the pupal stage, the fly surfaces from the pupal case by breaking it with help of its ptilinum. Ptilinum is a sac which swells and shrinks alternately. It is located on the front of the fly’s head and it uses ptilinum as a hammer to smash the pupal case and emerges from it as a complete adult fly.
The size of an adult house fly is about 6 – 7 mm long with females bigger in size as compared to males. Another feature which distinguishes females from the males is the wide space between the eyes of female flies. Adult house flies have sponging mouthparts and reddish eyes.
The lifespan of adult flies is about 15 – 25 days. If the conditions remain favorable with a continuous supply of food, they can live up to 2 months, but won’t survive more than 3 – 4 days without food.
Development of a fly from an egg to an adult fly can take several days to several weeks. It depends on the temperature and surrounding conditions and if the conditions are favorable the fly can complete its life cycle in a couple of weeks. Besides the surrounding conditions, the species of the flies also determine its life cycle.
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