Tell us more about your garden. What are you growing, and what are you using on the garden as far as chemicals or organic amendments and treatments? Are you allergic to anything?
Do you have any sense if it is a flying insect or crawling? Do you see a pattern of bites/stings or are they widely distributed on your skin? Does wearing long sleeves, etc, always prevent the bites or spots?
That blister looks kind of like the poison ivy spots I get if I'm in the woods near the house and not being careful. Do you have any poison plants in the area?
I'm growing a variety of heirloom tomatoes, eggplants, peppers, radishes, and basil. I am following an all-organic approach and have used the following products in the garden:
Composted horse manure
Organic cotton-burr compost
Texas green sand
and that's pretty much all I can recall.
I try to wear long sleves, cloves, warm-ups, etc, because I got slammed hard with this rash last year right after we moved in and I started my garden. Actually I first encounterd the issue when removing a pile of bricks stack against the very same fence my garden is near.
I have only once noticed a bite the same day, and thought it was a mosquito. I want to say that the area is without poison ivy, but I'm not 100%. My neighbor on the other side of the fence has also had the very same rash when she worked in the same general area.
Most of the time I will break out around my wrists, shins, or lower arms. This time I have one on the inside of my thigh, knee, and upper leg. I was in shorts the other night while troubleshooting an issue with my a/c for approx 30 minutes. (Which makes me think it might be insect related)
No known allergies other than cats and dairy. I react "normally" to mosquito and ant bites.
So to sum it up, it can happen if I am on my knees working in the dirt, carefully walking through to pick some yellow-pear 'maters, or standing in a particular area of the yard for some time.
Lol, the people at work must think I'm in a fight club on the weekend as I come in with band aids all the time!