Sergi and the Tabasco Sauce Solution

Riddling the last week of fun and games with Iffar and Elina was a joke about the fly in the soup . . .

Customer in restaurant:  Waiter, what is this fly doing in my soup?

Waiter:  It looks like it's doing the back stroke.

The joke, no matter how many times it was told at the table on the front porch, brought forth gales of laughter from the little ones who told it.  Perhaps because they had just returned from summer camp where there had been plenty of flies; perhaps because they had just spent a week doing the back stroke. Hopefully not because they had seen flies in their soup.

None the less, when Marash Girl and Ranek were having lunch at Legal Seafoods in Framingham, a black fly insisted on visiting their table.

"Waiter, there's a fly buzzing around our table."  The waiter, rather than suggesting that the fly was doing loop-de-loops to entertain us, simply answered, "I'll get the Tabasco Sauce."  

Nonplussed, Ranek and Marash Girl looked at each other, and at the fly as it continued to loop-de-loop around the corner table at which they were seated.

Soon the waiter returned with a saucer that had been splashed with a teaspoonful of Tabasco Sauce.  He placed the saucer on the table, and . . . .

The fly fled .  . . And never returned.  

Can anyone out there explain the chemistry of this miracle cure?