I am the token tick, chigger, and mosquito bait at family gatherings. The little bastards love me. Mom can walk through grass barefoot and in shorts. Nothing. Not so much as an itch or a single skeeter. Me? I can sit on the porch in jeans, hiking boots, crew socks, soaking wet in Deep Woods Off, and still be in a cloud of mosquitos with solid chigger bites up to my knees.
Best way I've found to curb (most of) the agony from chiggers is soak cup towels in rubbing alcohol, place on the affected area, then wrap snugly in plastic wrap. Leave for five minutes. This seems to kill any remaining critters and maybe dilute or remove the offending saliva. Then I double up on diphenhydramine and lather on antihistamine cream. Doesn't take all the itch away, just makes it tolerable enough to not rip my skin off. Also makes for a nice nap.
Brad