Spiders everywhere!

Why is our balcony like a spider colony? I went out there and saw a few so I got the bug spray but then a few more crawled out nearby so I just started spraying all over the railing and spiders started crawling out everywhere! There was easily 20 of them and one was HUGE, it was a nightmare! I think I got all of them except this one which was hiding on the other side of the railing and I don't want to reach over the edge.