Now, I grew up in Australia, so I fancy myself used to spiders, cockroaches, and flies. I once spent a rather uncomfortable night, when a student, sleeping in a friend's spider-infested room, and endured an entire summer house-sitting a flat that was so badly infested with cockroaches that they woke me in the night, scuttling over the sheets. And now, in an old house in the English countryside, I usually wack an average of one spider a night.
But I'd rather not have them taking up residence in my potting shed. I did a bit of research, and it turns out that vermiculite is not just a sterile material for horticulture, it's also a sterile nesting material for arachnoids. I've replaced it, and housed it in sealed containers instead.