My son was bitten while camping on the weekend. Most were normal itchy mosquito bites but 2 are fluid filled blisters - 1 has grown quite big, the other stayed smaller. It is really puffy. We went to the Dr. Yesterday and he said definitely not a mosquito, but hadn't seen it before so couldn't tell what it was. So, once again, I'm researching myself and as far as I can figure it is a spider bite of some kind. It's the only insect I'm finding consistently that can blister. It seems no need to worry unless showing signs of infection - but it's pretty creepy. We're on Vancouver Island so I may look into the species we have here. Good luck to you ;)