The claim that honeybees have an "odometer" based on "optic flow", is just
one of very many silly, groundless, conclusions that owe their origin to v.
Frisch's stillborn, never experimentally confirmed, "dance language"
hypothesis.

Very, very briefly, when the foragers fly to food & back through a very
long, narrow tunnel, with a complex bacground pattern, they indicate in
their dances a far greater distance than actually flown. This, however, has
nothing to do with any "odometer". When they fly through such a tunnel, the
bees are obliged to fly much more slowly than normal, to avoid crashing into
the walls. This has a double effect on energy-expenditure: It requires the
bees to spend more energy per unit time, to merely stay aloft, and also
lengthens the duration of the trip.

The authors never considered such an a possibility, and, therefore, did not
bother to measure flight-speeds, which could have been done very easily.
(The bees were allowed to see the sky through an insect-net that covered the
top of the tunnel; which meant that the scientists could see the bees flying
inside the tunnel.) The lead author, (Srinivasan), however verified for me,
(in an e-mail years ago), that the bees indeed flew visibly much more slowly
inside the tunnel with the complex bacground pattern, than with the simple
pattern.

-- 
Sincerely,
Ruth Rosin ("Prickly pear")

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