Hey. I feel your pain, literally... just got my 3rd case of the year... the bad news is that despite living and working in the south for the majority of the past 30 years, you can't escape them completely. the good news is you can minimize their effects.
My urge to scratch the itch has largely subsided. And you are right, I seem to be less sensitized (or more inured) to chiggers later in the season. Mosquito bites don’t bother me nearly as much as chiggers, perhaps because I am mosquito exposed 9 or 10 months a year. Chiggers are more of an occasional problem.
First layer of defense is behavior, which you seem to have down... no sitting on the ground, hammock, chair, stay out of their home.
I expect that I know from experience where my exposure this last trip comes from. We had a passel of young kids along on a group trip and my hammocks were in constant kid use (I actually brought three, and rarely found one empty to lay in). Those hammocks were often found to be filled with dust and dirt from kid shoes and clothes.
We also had a retriever who loves to play fetch, invariably depositing the dirt covered stick in my lap for yet another throw.
The worst case of chiggers I have ever seen was amongst a family with whom we tripped, who brought their dig-a-hole-and-lay-in-it German Shorthair and slept with her in the tent.
The worst case I’ve ever had was from the fetch happy retriever, who when ignored would bury my feet in pawed dirt, demanding another throw of the stick.
At this point I’m convinced that dogs in chigger country can be a bad combination. And that any recently disturbed ground is best avoided.
The worst part of chiggers to me is the “never know where” aspect. I’ve done ill-advised plumbing repairs in the crawlspace of southern homes and escaped unscathed, and done carefully elevated swamp campers and endured a weeklong itchy ring of bites in every area where elastic touched my body.
For those who don’t know chiggers they favor digging in around socks, and especially under the elastic waistband of underwear. As a supposed professional coming back from a trip only to be constantly scratching at my nether regions was not a good look.
I believe one preventive solution is loose fitting clothing, and where possible avoiding the compression of elastics. Going barefoot and commando helps. Maybe going buck naked would offer the best approach. I wonder if chiggers are less problematic in southern nudist colonies?
Second layer of defense is Permethrin. getcha some, use it. Everything but underwear and t-shirt... socks, fabric parts of boots/shoes, pants, outer shirt, hat, pack, and hammock.
I’ve got some and will be applying to various items of gear at the next opportunity. I’ve actually had it for several months, but Permethrin is toxic to fish and other aquatic organisms, and especially toxic to cats, and that precludes using it at home among the aquariums and the shop coon cat.
http://en.wikipedia.org/wiki/Permethrin
I’ll try it on the hammocks and the chairs, specific clothing items, hats and shoes (the straps on sandals and flip flops are another chigger target) and the UV lap blankets, which might then serve as bug shields as well as sun shields.
3rd layer is treatment... the reason the bites itch supposedly has something to do with a small air tube that gets formed when the chigger buries himself in your skin. I have used ammonia ("Itch Away" is a product sold commercially for this) with some success. Cortisone crème helps a little, or Lanacaine.
Yeah, chiggers are like something out of science fiction.
http://en.wikipedia.org/wiki/Trombiculidae
I’ve use an Afterbite pen for relief, which I believe is largely ammonia based, and it works for a bit, and have Cortisone and Lanocaine in the group first aid kit. I do wonder if there isn’t some same-locale native plant remedy, something akin to Jewel weed for poison ivy.
When all prevention fails the best solution still seems to be the steely resolve not to scratch the itch. I’m still working on that.