black widow infestation! help!

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So my car has been sitting around for awhile. last winter break i was picking a bunch off black widows off the outside of my car and my door jambs for days, but since i got back 2 weeks ago and got it running and have driven it around, they've seem to dissapear. all of a sudden though, i'm seeing a couple around my garage and it's making me super paranoid. i searched a little bit but nothing substantial came up, so here it goes:
Have any of you guys had to deal with insects in your cars, and whats the best way of nuking them out of there? I'd hate to get punked by a black widow while working on my suspension... :-( oh btw, i've always washed the bottom with a hose, but it still does nothing to calm me down lol