A-z - Animals

Fly Lifespan: How Long Do Flies Live?

Updated: January 23, 2023

© Fotopstryk/Shutterstock.com

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Flies seem to live all summer, stalking humans in people's homes, on patios, and during delicious picnic lunches. But how long do flies live? These insects have shorter lifespans than you might think. A fly is any small winged insect in the order Diptera, which has more than 120,000 species. The most common fly is the housefly, which accounts for 90% of flies in human homes. Other flies you may be familiar with are horse flies, fruit flies, and tsetse flies. Two other flying insects that you might not know about also belong to the order Diptera, and they are mosquitoes and gnats. Given the variety of flies out there, it's worth asking the question — how long do flies live? Let's take a look at these flies and find out how long they live.

Housefly: Lifespan 28-30 days

animal with the shortest lifespan
Houseflies are found throughout the world as symbionts of humans. It is the most common species of fly in houses.

© Fotopstryk/Shutterstock.com

Houseflies are the most common type of fly and can be identified by their two wings, six legs, large reddish-brown eyes, and stripes on their chests. Houseflies are about the size of a fingernail, with females being slightly larger than males. They live in our homes, fly around our heads and try to land on our food, but they don't bite. They can spread disease by spreading contaminated microbes. For example, if they land on a pile of rotting garbage, get microbes on their feet, and then land on your corn cobs, you could be exposed to the same stuff, which could make you sick if exposed in large quantities. The fly life cycle is similar in most species. They go through 4 cycles as follows:

  • Egg stage : Females lay about 100 eggs at a time, which hatch within 12-24 hours
  • Larval (maggot) stage : Maggots are small, white, worm-like. During this feeding stage, larvae will grow to ¾ inch or more. This stage may take 4-7 days.
  • Pupal stage : At the pupal stage, the fly looks like a dark brown cocoon, which develops for 4-6 days at this stage.
  • Adult stage : After the pupal stage , adults emerge with a life expectancy of up to 28-30 days. Females take an average of 12 days after maturity to lay eggs.
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The life cycle of flies is repeated from generation to generation, and a female fly will lay 5-6 batches of eggs in her lifetime.

Horsefly: Lifespan 30-60 days

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Horse flies that feed on their magnificent eyes.

Horseflies are similar to houseflies in that they have similar life spans. They are larger than houseflies and can grow to the size of bumblebees. They are named for being common around stables and harassing horses in the fields, not only harassing them, but biting them. Horseflies are blood-sucking animals that use the proteins in their blood to fertilize their eggs. They also bite. While the bites are harmless, they do injure and cause itching afterwards. Bites from horse flies can be dangerous to horses because they carry "equine infectious anemia," which can cause fever and illness in horses. Farmers and ranchers often cover their horses with thick blankets to help deter horsefly bites.

The life cycle of the horsefly is very different from that of the housefly. They lay eggs on grass in the fall, and the eggs hatch and become larvae in winter. In the spring, the horsefly develops into a pupal stage, and by early June it becomes an adult. Adult horse flies have a life expectancy of 30-60 days.

Drosophila: Lifespan 40-50 days

animal with the shortest lifespan
In most cases, fruit flies should be considered beneficial insects. The decaying matter they eat can become a source of fungal or bacterial infection, or attract more unwanted pests, such as mice or rats.

© Jordan Lye/Shutterstock.com

Fruit flies are small flies you might see around fruit bowls on the counter, especially if you have ripe bananas. These little flies can reproduce fast! Their lifespan includes egg, larva, pupa, and adult stages, but each stage is only a few days long, and they can go from egg to adult in as little as a week. Once they are adults, they can live for 40-50 days

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Tsetse fly: 14-21 days (male); 1-4 months (female)

The deadliest animal in the world: the tsetse fly
Tsetse flies live in Africa, in wet areas along rivers and lakes. They are the size of a giant fly and only feed on blood.

©Jaco Visser/Shutterstock.com

Tsetse flies are not a problem in North America as they are only found in Africa. The female tsetse fly is one of the longest-lived flies, living 1-4 months. Tsetse flies are a big problem in Africa because they carry a disease called sleeping sickness. It is fatal if left untreated, but there are drugs that can cure it, but tsetse flies also attack livestock and other animals, leaving them to a fatal end. Tsetse flies have one of the most unique life cycles. Female tsetse flies have a uterus in which their larvae are born. The larva grows inside the female for about 9 days, then burrows into the ground when it is born to complete the pupal stage. It spends 3 weeks to a month in the pupal stage before emerging as an adult. Adult males have a short life span of 14-21 days, while females live 30-120 days.

Small insects: lifespan 7-14 days

Fly Lifespan - Gnats
Gnats only live for two weeks

©Henrik Larsson/Shutterstock.com

Gnats are those annoying little bugs that fly around your face at bus stops. They are not larvae like some people think. They are their own species and share similarities with the housefly. Gnats as a group have one of the shortest lifespans, with some living as little as a week. Fungal gnats are commonly found on houseplants and can also be found through houseplants in the lobbies of commercial buildings. As the name suggests, they feed on the fungus that develops when these plants are overwatered. Gnats have a life cycle similar to fruit flies, lasting anywhere from one to two weeks. Likewise, the lifespan of an adult gnat is 7-14 days.

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Mosquitoes: Lifespan 10-14 days (depending on temperature)

Animals that can see infrared light Mosquitoes
Mosquitoes are the deadliest animals in the world because they spread all deadly diseases.

© iStock.com/nechaev-kon

Mosquitoes are flies! A common summer pest, they have long, thin legs so they can land on you without you noticing. Only the female bites, but the resulting bite is itchy and painful for several days. This is the most common result of bites, but they can carry diseases such as Zika, West Nile and malaria. According to the CDC, "…most people infected with West Nile virus do not feel sick. About one in five people infected develop a fever and other symptoms." Mosquito Life Cycle and Home Flies are similar, but eggs must be laid in standing water. The eggs hatch in water and the larvae are aquatic, meaning they live in water until they reach the pupal stage. It spends several days in the pupal stage, and the adult emerges ready to fly. Adult mosquitoes lived longer (14 days) in cooler temperatures and shorter (10 days) in warmer temperatures.

So how long do flies live? From our analysis, it can be seen that the time will not be very long. Horseflies live the longest, up to 60 days. The most annoying species to humans, the common housefly, only lives a month at most. But flies can certainly cause a lot of havoc in that time span, and when you consider that a large collection of flies, all of varying ages between them, can mean months and months of annoyance!


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animal with the shortest lifespan
Houseflies are found throughout the world as symbionts of humans. It is the most common species of fly in houses.

© Fotopstryk/Shutterstock.com

about the author

I'm a wildlife conservation writer and reporter who raises awareness about conservation by teaching others about the amazing animals we share our planet. I graduated from the University of Minnesota Morris with a degree in Elementary Education, and I am a former teacher. When I'm not writing, I enjoy going to the kids' soccer games, watching movies, working on DIY projects, and running with Tango, our giant Labrador.

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