In a message dated 12/04/02 05:04:28 GMT Daylight Time,
[log in to unmask] writes:

<< How do bees and other animals detect air pressure changes?   >>

They do have internal air sacs in their abdomens.  Presumably a sudden drop
in external air pressure would cause the internal sacs to expand and give the
bees a sensation, tummy ache perhaps, that suggests they head for home.

Chris