"Red bugs" or chiggers are too small to see without magnification.
They are related to spiders and require a host (squirrels, birds,
deer, reptiles, or humans). You can get chiggers by sitting on the
grass or walking through tall grass. The larva can crawl from your
foot to your underpants in 15 minutes and they look for a place to
burrow in, usually a crease or under an elastic band. After burrowing
in they spit their saliva which dissolves flesh, then they drink it.
One chigger only has one bite site. After several days of feasting,
they fall off the host, find a mate, and lay eggs on the ground where
the larva emerge and the cycle starts again. They are more of a
problem during warm days (>70 degrees). Often chiggers will
congregate on one blade of grass, waiting for a passerby. The site
of the bite turns red with a white center, much like a mosquito bite,
and the itching lasts for a week or two. Use 91% alcohol (or I use
"Absorbing Jr.") applied to the site for several minutes should kill
the chigger. Scratching can infect the bite--don't do it.