Just something I've been discussing with a number of people and feel like cross posting:
For the last time, arachnophobes: it's not a "natural instinct." There are no spiders on Earth dangerous enough for a knee-jerk terror of them to have ever been a useful survival trait. What you have is a mental illness, and it's only commonplace in highly developed countries where so many children are raised in an anti-nature bubble. Just accept that your fear is a sad, unfortunate disease and stop attempting to pass it off as logical.
The same can be said for any aversion to any living organism under a fifth your size. Your ancient ancestors were cracking open the skulls of cave bears, not jumping up on cave tables demanding Thog squish a cockroach for them.