How Far Can Flies Smell?
WouterFlies have an incredible sense of smell. They can detect odours up to 7 kilometres away. Their antennae are covered with olfactory sensory nerve cells that detect volatile chemicals. The odours that flies pick up diffuse into tiny pores and then bind to receptors on olfactory neurons. These neurons then send signals down the sensillum to the brain. The distance a fly can smell depends on several factors, including its size, local topography, and the direction of the wind.
Flies can smell decomposing flesh eight to 10 miles away. They can also migrate quickly enough to reach a body within hours. Because they feed on dead flesh, they can provide vital clues in a suspicious death. Different species of flies colonize a decomposing body at different stages of its life cycle. They can tell forensic investigators whether the body was moved after death, and whether toxins were present.
Insects use their keen sense of smell to find food and mates. Their ability to smell airborne substances helps them locate these resources and avoid predators. Moreover, their ability to detect chemical cues helps them locate their nest or space themselves in habitats with limited resources. For instance, a fly’s wings have tiny pores called nanopores.
Scientists have a long-standing goal of understanding how flies sense smells. One of the first steps toward this goal was to discover the specific sensory neuron that is responsible for detecting CO2.
