DIY spider killer?
My results have been fantastic. I spray once or twice a year. Normally I spray in spring, outside and inside (only the basement, fully unfinished) I go pretty heavy on it, I use 1oz in 1gal of water. Usually 2 batches total. Though last year I took it easy and ended up using 1 gal for both in and out. I sometimes do it in the fall too as spiders are looking for a place to stay for winter, but this year I never ended up doing it, and I was also curious to see how effective the last spraying would hold up.
I have to say, I'm impressed. I still see an occasional spider web here and there, but it's way better than what it was before. The crawlspace under my garage also remains more or less untouched. I will always see a few webs here and there but it's far from what it used to be. Like, it was BAD. Even after I cleaned it, it only took a year for it to get almost as bad as what it was. Since I sprayed, it's much better.
I'm due for another application, but I'll probably wait till spring so it's more fresh. There wont be any new spiders coming in at this point, and any existing are most likely dead.
After an application I always find dead spiders here and there, also dead centipedes, pill bugs, and other random insects. The stuff really works.
As for the sprayer, I just got it at Canadian Tire. Look in the pest management section of any hardware store and it will probably have one, if not, maybe garden, for fertilizer spraying. Same idea, just a pump sprayer. Works pretty good.