I think fear of snakes/insects is an instinctive, protective reaction; a hangover from when very many of them WERE harmful to us. And of course, in some places they still are.
But a natural fear is not the same as a phobia, which is an exaggeration of that instinctive fear, and is usually triggered by a childhood event.
Other people seem to have 'mislaid' the instinctive fear reaction, and others have learned to control phobic reactions. I'd get my spider phobia back pdq if I went to a country where they were poisonous!
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Dubbed Queen of the Illuminati by Diogenes.