The locals call them "guinas" which I think translates to "chigger" but not sure. A number of people have recently been getting them after walks to the water holes. To get rid of them, without using chemical substances, you can wash laundry the exposed clothing lots of detergent and let the clothes sit in the soapy water for at least 24 hours. To treat the bites on the body, put lots of tobacco in 96% alcohol which you can buy at the corner liquor store by the plaza. Let the tobacco leaves sit for 48 hours in the alcohol then rub the alcohol liberally on your body throughout the day.
Hope this helps!