The Worst House Guests
Houseflies. They are everywhere and anywhere.
Believed to be native to Asia, houseflies now inhabit nearly every corner of the globe. Except for Antarctica and a few islands, houseflies live everywhere people do. Houseflies are synanthropic organisms: they benefit ecologically from their association with humans and domesticated animals. Conversely, houseflies are rarely found in the wilderness or in places where humans are absent. Should humankind cease to exist, houseflies might share our fate.
They procreate anywhere too, as and when they wish, laying their eggs even in feces. Their rate of reproduction is so fast that, if not for environmental conditions and predation, houseflies would perhaps rule the world.
Houseflies breed in the things we revile - garbage, animal dung, sewage, human excrement, and other nasty substances. While living among these filth, they feed on them too. With sponge-like mouth-parts, houseflies soak up liquefied substances. When a housefly locates something tasty but solid, it regurgitates onto the food. Its vomit contains digestive enzymes that quickly predigest and liquefy the food for the fly suck it all up.
Other than its gross vomits, houseflies poop a lot too. Nearly every time a housefly lands, it defecates. So, the housefly almost always does poop where it eats. Keep that in mind next time when one touches down on your favourite meal...
Something to ponder
1. How do houseflies decide something is appetising?
2. How do houseflies transmit diseases?
They step on it! Like butterflies, houseflies have their taste buds on their toes, so to speak. Taste receptors, called chemosensilla, are located at the far ends of the fly's tibia and tarsa (in simpler terms, the lower leg and foot). The moment they land on something of interest – your garbage, a pile of horse manure, or perhaps your lunch – they start sampling its flavour by walking around.
Houseflies thrive in places that are teeming with pathogens, hence they have a bad habit of carrying disease-causing agents with them from place to place. A housefly will land on a pile of dog poop, inspect it thoroughly with its feet, and then fly over to your picnic table and walk around on your hamburger bun for a bit. Their food and breeding sites are already overflowing with bacteria, and then they vomit and defecate on them to add to the mess. Houseflies are known to transmit at least 65 diseases and infections, including cholera, dysentery, giardiasis, typhoid, leprosy, conjunctivitis, salmonella, and many more.