Dog is anxious when flies get in the house

[Bobbi]

As indicated my mixed breed Foxy becomes extremely anxious on the rare occasion the a fly gets in the house. All of her training goes out the window! She will not down, sit, and especially not come. She has a fairly reliable recall, but once that fly is in the house her anxiety is so high that she hears nothing. What can I do to help her become less anxious without making her more anxious?

Thanks in advance for any and all ideas.