I was bitten in the left foot by a spider 15 years ago. I watched the poison work it's way up my leg to the knee. and my leg was numb for 3 hours. Later I noticed that it had killed
a small ring of pigmentation around the bite. Anyway, I have been bitten at least 4 times
a year since the first bite, and always in my left foot, never any where else, no higher than the ankle. My question is, do spiders leave some kind of trace that attracts other spiders?

interesting...i wish i could help, but i will be tuning in!

Are you assuming that you're being bitten again because of localized swelling? Are you actually seeing something bite you each time?

Chances are that the original bite just never fully resolved and you're just having a recurrent localized allergic reaction. If it is causing you concern, see a dermatologist, who will likely perform a biopsy.