All about House Flies

The house fly, Musca domestica Linnaeus, is a well-known pest of houses (thus, the name) and farms. This tiny creature is very common and cosmopolitan in distribution. Chances are good that every human being in different parts of the world will have at least one encounter with this pest in his lifetime. House flies abound in every human habitation, breeding around houses, in garbage dumps, animal manure or wherever there is decaying organic matter.

Taxonomically, the house fly belongs to Phylum Arthropoda, Class Insecta (Hexapoda), Order Diptera and Family Muscidae. Descriptively, house flies have six jointed legs and two membranous wings. Unlike other insects, the hind wings of dipterans have been modified and reduced into halteres, which are club-shaped sensory organs essential for flight control and stability. Although many insects are called “flies”, only those belonging to the Order Diptera are referred to as “True Flies.” As explained by a former professor, this is the reason why house fly can be written as two separate words, as in “house fly”. In the case of butterfly, firefly or dragonfly separating the word "fly" doesn’t make sense because they are not true flies in the first place.


Description, Biology and Behavior

How they develop contributed much to their success as an organism.  The house fly has a complete metamorphosis.  It has distinct egg, larva, pupa and adult stages.  It may take about 7 to 10 days for an egg to become adult under optimum conditions and up to two months when conditions are suboptimal.  Generally, developmental periods are shorter with warmer temperature.  This link illustrates the impact of temperature on developmental period.

Eggs are laid singly but piled in small groups. A female fly can produce around 500 eggs and lay them in batches of about 75 to 150 over a three to four day period. House fly eggs are tiny (about 1.2 mm), white and elongated. They should remain moist to maintain viability but under favorable conditions, they can hatch as quickly as 8 hours to 3 days after being laid but. Eggs are normally laid on nutrient-rich substrates, like animal manure, or your food for a picnic, that can provide an excellent medium for larval development when they hatch. You might want to consider food covers when eating outdoors.

Larvae of flies are called maggots. They are spindle-shaped, legless, creamy white in color and the head contains a pair of dark hooks. A pair of spiracular plates can be seen on the posterior end. Maggots immediately feed after hatching from the egg. There are three larval instars, which mean they molt or shed their skin three times but the third skin is hardened and used as puparium. Under favorable conditions, larval development may take about five days. For larval developmental periods at varying temperature, click this link. A mature larva measures 10-15 mm. Maggots leave the breeding material and moves to a dry, cool place when about to pupate.  Watch the video to see house fly maggots in action.

Pupa is the externally inactive stage. It is hard, shaped like a capsule and measures about 6 to 8 mm long. Its color changes as it matures; from pale yellow to red to dark brown that turns darker to almost black when adult is about to emerge. A pupa measures about 6 to 8 mm long. It takes about three days for an adult to emerge from the pupal case and longer if the temperature is cooler.Watch the adult emerge from the pupa.

Adult fly is gray in color with 4 dark bands on the thorax and has partly yellowish abdomen with a dark midline and irregular dark markings on the side. The wings are membranous and the sharp upward bend of the fourth longitudinal vein is very apparent. House flies have sponging mouthparts, which is not capable of biting people or animals. They suck in liquids like a sponge and liquefy solids by regurgitating intestinal fluids on the food before sucking them in. Watch this brief video of a housefly feasting on a sugar crystal.  House flies have compound eyes comprising thousands of individual lenses. They can recognize movements in a full 360-degree spectrum allowing them to see a far wider range and react quickly. This is the reason why it is extremely difficult to swat a house fly.

The adult fly may measure from 6 to 12 mm, depending on larval nutrition but males are usually smaller. However the best character that differentiates the male from the female is the distance between the compound eyes. While the eyes are almost touching in the males, there is a relatively wider space between the eyes of the females.

Females may start to be receptive to mating in about 28 hours from emergence and they require food before copulation. For a more detailed house fly mating behavior, please visit this link. It was observed in this study that flies may remain in coitus for up to 96 hours but complete sperm transfer requires only about 10 minutes or less and no sperm transfer occurs in less than 2 minutes of copulation.

They are active at daytime and rest at night. Adults may live for several weeks or even up to two months depending on food availability. They survive for only two to three days without food.

Why House Flies are Considered Pests?

The obvious offense that house flies do to us is nuisance…they are definitely annoying, especially when they disturb us in our sleep.  A graver consequence of house flies in human habitation is the potential for disease transmission.  House flies are very well known carriers of pathogenic microorganisms because of their food preference and manner of feeding.  When a fly feeds on infected human or animal faeces, it takes the bacteria into its gut.  Microorganisms also adhere to the different parts of its body like the tiny hairs on its footpads.   Then, if it feeds on food to be consumed by a human (no cooking or heating prior to intake), it lands and transfers whatever microorganisms are on its body surface then regurgitates fluid over the food including the bacteria accumulating in its gut.  In this manner, they can transmit enteric diseases, intestinal parasitic worms and are also linked with Typhoid and Cholera.

House fly existence is of economic importance in livestock and poultry farms.  Damage is also done through annoyance and disease transmission.  General annoyance has been associated with reduced milk production in cattle and egg production in chicken.  Stress levels due to annoyance also affect growth. 

Products Dedicated to House Flies

The significance of house flies in human life is undeniably soaring as evidenced by the voluminous amount of work done to study them, the huge industries that have been created to control them as well as in the large amount of products dedicated unto them.  I bet these products were not produced to glorify them but to acknowledge their existence and irrefutable significance in society.  House flies are here to stay. Though they connote filth, they are part of natural history and offer challenges to human capabilities.  After all, the gruesome things we blame them for are only consequences of their natural biological make-up and the negative impact on human beings are unintentional.  Below are some products available at Amazon that you might be interested in buying and collecting.

The House Fly Documentary

Management of House Fly Populations

If we are convinced that we should get these flies out of our way, several techniques are worth considering like sanitation and cultural control, physical control, trapping, biological control and chemical control or design an integrated fly control program. Due to hub –size management, details of this topic will be posted in another hub. For the meantime, learn house fly management strategies from this documentary.

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ChristineVianello profile image

ChristineVianello 5 years ago from Philadelphia

This hub is very interesting. I acutally fear flies more then anything in the entire world. I did watch the videos you put up and they freaked me out. But I was still very interested. ha

Katy 5 years ago

Wow, very interesting. I already think fly's are gross and disgusting, and now reading this makes them even more nasty!! :x

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