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Amphion floridensis
Oh my, I am embarrassed. After checking I think you are correct about it being Amphion floridensis
Macroglossum hirundo is an Australasian species and not found in Texas. Despite the bad condition of yours I think it might be Amphion floridensis. Check the white lines (2 on the body) and some other white markings, scalloped shape of the wings and some orange markings. Please, verify!
http://bugguide.net/node/view/3131