House-fly

• It can mechanically transmit more than 100 different pathogens.
• Its whole cycle from egg to adult can take only 7 to 10 days in ideal conditions.
• It feeds by suction and cannot take in solid food.
• It cannot chew: it only ingests liquids. It regurgitates saliva and digestive enzymes onto solid food, dissolves it and absorbs the result with a spongy proboscis. That is why it is so effective at transmitting pathogens.
• More than a hundred pathogenic organisms have been attributed to it, carried on its legs, body and digestive tract, among them those of salmonellosis, dysentery, cholera and tuberculosis.
• It tastes with its feet: its chemoreceptors are on the tarsi, so it knows whether something is edible the moment it lands on it.
• Its life cycle is dizzyingly fast: from egg to adult in under a week in warm weather, and a female can lay several hundred eggs. Under ideal conditions a single pair would leave an astronomical number of descendants in one season.
• Its compound eyes have some 4,000 facets and a visual refresh rate three times the human one, and that is what makes it so hard to swat: it sees the fly swatter coming in slow motion.
• The larva is now mass-reared as a protein source for animal feed and as an agent for treating organic waste.

Skeleton type

Invertebrate - chitin exoskeleton (insect)

Habitat and environment

Practically cosmopolitan, closely tied to human settlement, farms and decaying organic matter the world over

Birth weight

A white egg roughly 1.2 mm long

Size at birth

A fast-growing maggot, 3-9 mm on hatching and 7-12.7 mm in the final instar

Sexual maturity

Reached once metamorphosis is complete, between 4 and 12 days after emerging as an adult

Gestation / incubation

Egg: 8-24 hours | Larva: 3-7 days | Pupa: 2-6 days (a full cycle as short as 7-10 days in ideal conditions)

Litter / clutch size

75 to 150 eggs per clutch, and 350-1,000 in a female's lifetime

Sources consulted: Koppert Biocontrol; UNH Extension fact sheet; LSU AgCenter; Animal Hype; ScienceInsights; Fly-Trick; Virginia Tech Extension; PMC (insect growth regulator resistance study); Animal Diversity Web, Musca domestica; Nature 181, 787 (curvas de supervivencia)

Best time: Most abundant in the warm season, although some adults survive the winter in temperate areas. Its optimum lies between 10 and 26.6 °C: below 7.2 °C it becomes inactive and it dies below 0 °C or above 44.4 °C