chigger        
noun [ C ] uk/ˈtʃɪɡ.ər/ us/-ɚ/
 (also chigoe flea, /ˈtʃɪɡ.əʊ/); (also jigger, uk/ˈdʒɪɡ.ər/ /-ɚ/)沙虱,砂蚤 
a type of flea (= very small jumping insect) that lays eggs beneath an animal's or person's skin
  US (also harvest mite)恙虫 
a type of mite (= very small animal similar to a spider) that lays eggs under an animal's or person's skin causing small red bumps that are very itchy (= you want to scratch them)