I HATE those little buggers.

Got into a mess of them while stalking a hog earlier this year in Texas. I was ready to go after the itchy parts with my hunting knife to make it stop.

The best relief I have found is very hot water (this works for poison ivy, oak, sumac, etc... as well).

Start the water running warm and put the affected part under it. Continue to raise the temperature slowly until you can no longer stand it. It seems to kill any and all itching for a number of hours. The longer you can endure the temperature, the longer you will get relief.