While walking west of Ajalpan, Puebla, Esme and I saw many bright red colored velvet mites (family Trombidiidae) walking around. That it just had stopped raining was probably the main reason for those beautiful small animals exploring out in the open. While I didn't actually measure any of the velvet mites we encountered, I estimate the body length of the animal in the above photo to be just over 1 cm.
This photo is part of the blog entry Velvet mites and cactuses, which has habitat photos and describes the environment.