When do fleas click? - briefly
Fleas generate a click during the mating ritual, when the male rapidly vibrates his abdomen to signal the female. The sound precedes the male’s attempt to mount and copulate.
When do fleas click? - in detail
Fleas produce audible clicks during the rapid extension of their hind legs, which initiates a jump. The click occurs at the moment the elastic protein resilin releases stored energy, propelling the insect into the air. This event follows a precise sequence:
- Sensory detection of a host’s vibrations or heat triggers the neural circuit.
- The flea contracts its femoral muscles, loading resilin in the tibial joint.
- A latch mechanism holds the tension until a trigger neuron fires.
- The latch releases, resilin snaps back, and the click is generated.
The interval between stimulus detection and the click is measured in milliseconds, typically 20‑30 ms for a mature adult. Temperature influences the timing; higher ambient temperatures accelerate muscle contraction, reducing the delay to about 15 ms, while cooler conditions can extend it to 40 ms. Age and nutritional status also affect the speed of the latch release, with younger fleas exhibiting slightly longer latencies.
In laboratory recordings, the click frequency aligns with the flea’s jump frequency: each jump is accompanied by a single click, and successive jumps occur at intervals of 0.5‑2 seconds depending on host movement. No additional clicks are emitted during grooming or feeding activities.