Flies, especially blow flies (family Calliphoridae), have an extraordinarily keen sense of smell for detecting decomposing flesh. They can smell decaying bodies from distances ranging generally between 7 kilometers (about 4.3 miles) and up to 10 miles (approximately 16 kilometers) under very favorable conditions such as wind direction, size of the carcass, and landscape features

. Key points include:

• Blow flies can detect the smell of decomposing flesh from up to 8 to 10 miles away, and they can migrate quickly enough to reach the source within a few hours

• Some studies and expert observations report flies finding dead bodies from about 7 kilometers away, which is roughly 4.3 miles. This distance requires substantial odor sources, such as a large amount of rotting flesh like a dead animal or poultry farm

• The flies' antennae contain highly sensitive olfactory sensory cells that detect volatile chemicals emitted by decomposition, enabling them to locate carrion from long distances

• The exact distance a fly can smell decomposing flesh depends on environmental factors like wind, terrain, and the size of the decomposing material

• Blow flies are usually the first insects to arrive at a corpse, often within minutes to hours after death, attracted by the odors released early in decomposition

In summary, flies can smell decomposing flesh from several miles away-commonly cited as 7 km (4.3 miles) to as far as 10 miles (16 km) under ideal conditions-and use this ability to locate carcasses quickly for feeding and egg-laying purposes.