Until first scratch. The missouri dept. Of conservation says chiggers are baby mites that can only bite through areas of thinner, tender skin (so chiggers like women & children). Chiggers bite to inject saliva to dissolve flesh and eat it up. They do not suck blood nor burrow into the skin. Once scratched, the chigger falls off easily, but the site swells, and itches a lot. A scrubby, soapy bath washes away chiggers.