Back in Las Vegas we used to go spider hunting at night with a flashlight and Raid (or carb cleaner) just to keep the black widow population down. Neighbors had a junkpile in their back yard, and we'd get new batches of spiders and webs along the fences every week or so. If they hadn't had kids and a dog in the back yard we would have tossed a couple of spider bombs into the pile, but we couldn't.
I bought a '73 Dart from someone who had just brought it from New Jersey when the Challenger had freeze plug problems. A week or so after I got it home I noticed a spider web in the rear window. Vacuumed it out. Next day three webs. Vacuumed out, checked the trunk, put a couple small squirts of raid. That night I had to drive somewhere, and saw something when I got to the car. Shown a flashlight down and saw many tiny spiderscoming out from under the car. Shined a flashlight under it and saw a nearly opaque mass of webs under the trunk, along the tank, with _thousands_ of baby spiders streaming down little strands, and the biggest, fattest, evil-est mama boack widow I've ever seen to this day. Bloody jersey spiders... no way that mass of webs and egg sacs were produced in the 7 days the car had been in Las Vegas.
For a while I consdered arson. Seriously (though is it arson if its your own car?). Settled for using up a can of carb cleaner on mama and all the areas I could see, borrowing another car, putting plstic drop cloths over the car and spider bombing it. Twice. Windows open since the little bastards had gotten inside two. Then I aired out the car for a few days before driving it again.
Spiders are evil. Black widows are uber-evil. And any spider in one of my Mopars is an affront not to be tolerated.
Unfortunately the modern effete "please dirt and varnish pretty please go away" carb cleaner is no more effective on spiders than it is on carb grunge so its Raid or nothing these days.