I scratch each bite until it bleeds. Usually works very well for me......like they don't itch again until the scab drys out. A little morbid? Perhaps, but I'm telling you it works. Was taught this trick by an old piney.
I agree, though, that this year they've been especially ferocious since there's so many of 'em. Needless to say, I've bled a lot lately.
I try to stay out of the woods until October 15 in order to avoid chiggers. Either this works or I have been extremely lucky for a long time.