Yes indeed. It makes sense if spiders are all dangerous poisonous buggs. From my region I have 1400 species of spiders. Only 2 or 3 are potentially dangerous for human. Most of these huge species number are sized below 3 mm.
It takes from your reply that these fears could be linked to instinct but unlikely with education (and/or belief). You could be right. But I still find this fear so irrational that I think it is good to investigate another irrational field (supernatural). Must be something there.