http://www.abc.net.au/science/articles/2011/06/21/3246956.htm

The researchers then demonstrated that stimulation of the wing
hairs, with brief puffs of air from different directions, led to stimulation of
the sensory nerve cells at the base of the hairs. This was distinct from tactile
responses due to physical indentation of the skin in conditions of high level
airflow.

Thanks to Kris.