I don't remember a Mothra from Scott, or anywhere else.  Ayers did work upon a Mecha-Godzilla, but he never released it as it exceeded his personal limit of file size.

Say, have you tried running a forum search on the word "Mothra".  I'm sure any links derived are long, long "dead", but it may at least give you a lead.  Use a range of "0 days to 5000 days" to cover the history of Renderosity.

Sincerely,

Bill

Tempt the Hand of Fate and it'll give you the "finger"!