Housefly on a window pane

Houseflies (Musca domestica) are among the most common and familiar insects to humans. They live in almost every region of the world and are very well adapted to human environments. Although they are small, they play an important role in ecosystems - but also in the spread of disease.

Identification

• Size: 5 to 8 mm long
• Appearance: Grey-black body with four dark lines on the thorax, prominent red eyes, transparent wings.
• Lifespan: Approximately 2 to 4 weeks, but a female can lay up to 500 eggs during her lifetime.

Life cycle

1. Egg: laid in decomposing organic matter (rubbish, excrement, corpses).
2. Larva (maggot): feeds on the material in which it was born.
3. Nymph: stage of transformation.
4. Adult: ready to reproduce in a few days.

The complete cycle can take 7 to 10 days, depending on the temperature.

Role in disease transmission

Houseflies are mechanical vectors of many pathogens, as they land on rubbish, excrement or cadavers, and then on human food.

They can carry :

• Bacteria: Salmonella, E. coli, Shigella
• Intestinal parasites
• Viruses
• Worm eggs (helminths)

Associated diseases: diarrhoea, typhoid, cholera, dysentery, etc.

They contaminate mainly by :

• Contact of their legs or wings with food
• Regurgitation (they vomit digestive juices before absorbing food)
• Defecation (they defecate frequently)

Usefulness in nature

Although annoying, they also have ecological roles:

• Decomposition: They help to recycle organic matter.
• Food: They are a source of food for many animals (birds, spiders, amphibians, etc.).
• Scientific research: Their larvae (maggots) are used in forensic medicine and certain therapies (wound debridement).

Control and prevention

• Keep areas clean and dry (eggs need moisture).
• Use mosquito nets, traps, insecticides or repellent plants (basil, lavender, mint).
• Cover food and dispose of rubbish properly.
• Encourage the presence of natural predators (bats, birds).

A little anecdote

Houseflies are unable to bite, as they have no mouthparts for this purpose. They suck up food in liquid form. If they come across solid food, they ‘predigest’ it by covering it with digestive saliva.

(Source: ChatGPT)