Mom got ambushed by something at the mailbox on Thursday and this was how the lesion looked on Saturday. Lots of confirmed spider bites show expanding lesions like this one, but infections can do that, too. As we've seen before, the blister can come from a bite, an infection or something else entirely.
There are very few welts or lesions that can be positively identified as a particular bug or spider. So often, readers want to know what kind of bug did the damage, but the answer has to be: what kind of bug did you see biting you? If the critter wasn't caught in the act, then there is little chance we're going to solve the case.
Ultimately if the lesion keeps growing, starts oozing, smells bad, gets hot, turns black, starts bleeding, the victim gets a fever or starts showing other signs of an infection, it's time to go to the doctor.
Any opinions expressed here are for educational purposes only and are not intended for diagnosis.
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