several randy oliver snips followed > by my comments... 

It would take a while.  Bees, unless vigorously flexing their wing muscles,
breathe only once or twice a minute.  They are able to survive in the
winter cluster at a reduced oxygen concentration of around 16%.

The stimulus of introducing a repellent on a hot day would indeed likely
cause many bees exposed to the fumes to begin fanning, but the oxygen would
not suddenly disappear from their surrounding atmosphere.

Thus, I don't see evidence to support the asphyxiation hypothesis.

>well first off glad to see the thread has convert to the original question....  which you now have verified as 'yes this can happen'.... I have missed this conclusion up till this point in time..  you are however PRESUMING here that the bees would have to totally utilize the existing air when a more likely cause is the air was simply displaced when the product applied vaporized at fast rate and thereby forced any air from the hive.  at the point at which the air was displaced it would not take long for the toxicity of the compound to do it dirty work.

The most parsimonious explanation would be acute toxicity due to a sudden
off gassing of butyric acid fumes due to an unfortunate combination of
extreme environmental conditions and operator error.

>and of course operator error is something we often overlook in terms of toxicity and contamination in utilizing these kinds of products.  it is a relevant fact that some products used in beekeeping requires a bit of good common sense (which doesn't seem to be common at all) and some ability to read and think.  it is one thing for someone like Randy or Jim or anyone really on this board to use these products for there intended purpose but it is something quite different when you hand the product to employees who may not read well and in the current time frame may not even read English as a first language.  to someone apply Murphy's Law... things will go wrong and will go wrong at the worst possible time.

personally I will continue to use Bee Quick when I remove honey and avoid this potential kind of problem.    

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